feat(ui): Phase 30 ship-class calculator with goal-seek and reach circles

Fuse the standalone ship-class designer (Phases 17/18) into a sidebar calculator: live mass/speed/attack/defence/bombing results, a planet build-rate readout, single-target goal-seek, a modernization-cost mode, and auto reach circles on the map for the selected planet.

pkg/calc becomes the single source for the new math (no mirroring): extract BombingPower from the engine model and the per-turn ship-production loop from controller.ProduceShip into pkg/calc (engine now delegates), and add inverse goal-seek solvers in pkg/calc/solve.go. Thin-bridge the combat, planet-build, and solver functions through ui/core/calc + ui/wasm and rebuild core.wasm.

Remove the standalone designer view/route; the ship-classes table and the view/bottom menus open the calculator via a shared request store.

Docs: rewrite ui/PLAN.md Phase 30, adjust Phase 34 (realistic forecast + CAP/COL ownership), add ui/docs/calculator-ux.md, extend calc-bridge.md, fix navigation.md; remove ui/CALCULATOR.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/PLAN.md

@@ -1968,7 +1968,11 @@ Decisions baked into Phase 16 (vs. the original stage description):
 
 ## ~~Phase 17. Ship Classes — CRUD Without Calc~~
 
-Status: done (local-ci run 20).
+Status: done (local-ci run 20). Note: Phase 30 removed the standalone
+designer view/route described below and folded ship-class create/view
+into the sidebar calculator; the table's row-activate and "new" button
+now open the calculator. The table itself and the validator are
+unchanged.
 
 Goal: list, view, create, and delete ship classes through a
 dedicated table view and a designer view; numeric calculations are
@@ -2037,7 +2041,10 @@ Targeted tests:
 
 ## ~~Phase 18. Ship Classes — Calc Bridge~~
 
-Status: done.
+Status: done. Note: the live mass/speed/range preview built here moved
+into the Phase 30 calculator when the standalone designer was removed;
+the `ui/core/calc` ship bridge wrapped here is reused unchanged and
+extended by Phase 30 (combat, planet build, solvers).
 
 Goal: wire `pkg/calc/` ship math into the designer for live mass,
 speed, range, and cargo capacity previews.
@@ -3314,39 +3321,92 @@ Decisions:
    rendered result is verified by a high-contrast screenshot during
    development plus the existing fog / render-on-demand e2e.
 
-## Phase 30. Calculator Tab
+## Phase 30. Ship Class Calculator
 
 Status: pending.
 
-Goal: ship an independent calculator in the sidebar, callable from any
-view, exposing the full set of `pkg/calc/` functions wired through
-`Core`.
+Goal: replace the standalone Phase 17/18 ship-class designer with a
+fused designer + calculator living in the sidebar. It shows the ship
+design blocks, live derived results (mass, speed, attack, defence,
+bombing), and a planet build-rate readout, and adds single-target
+goal-seek — the player pins one result and the model back-solves the
+single input it claims. A second mode reuses the design area to price
+ship-class modernization. The standalone designer view and route are
+removed; the ship-classes table and the view/bottom menus open the
+calculator instead.
+
+The original four detached modes (ship / path / modernization /
+bombing) were dropped during planning: path is deferred (MVP path is
+brute force) and replaced by auto reach circles on the map; bombing is
+folded in as a per-ship result; ship and modernization are the two
+modes. See `ui/CALCULATOR.md` history (removed) and the interview
+decisions baked below.
+
+Goal-seek claim map (one lock at a time): attack → weapons,
+defence → shields, empty/loaded speed → drive, empty mass → cargo,
+loaded mass → cargo load. Locking one result disables the others'
+lock affordances; an unreachable target shows the locked cell in an
+error state. Tech levels and the planet MAT are override inputs with a
+reset lock; the player tech is the default.
 
 Artifacts:
 
-- `ui/frontend/src/lib/sidebar/calculator-tab.svelte` UI with mode
-  selector (ship calculator, path calculator, modernization cost,
-  bombing power) and per-mode forms
-- bridge entries in `ui/core/calc/` for any function not already
-  wrapped by Phase 18
-- topic doc `ui/docs/calculator-ux.md` documenting modes,
-  layouts, and the rule that calculator inputs persist across
-  navigation
+- `pkg/calc/` additions, single-sourced (no mirroring): `BombingPower`
+  extracted from `game/internal/model/game/group.go`; a pure
+  `ProduceShipsInTurn` extracted from `controller.ProduceShip` (the
+  engine now delegates to both); inverse solvers in `pkg/calc/solve.go`
+  (`WeaponsForAttack`, `DriveForSpeed`, `ShieldsForDefence` by
+  bisection, `CargoForEmptyMass`, `LoadForFullMass`)
+- thin bridges in `ui/core/calc/` (combat, planet build, solvers),
+  registered in `ui/wasm/main.go`, typed on `Core`
+  (`platform/core/index.ts` + `wasm.ts`)
+- `ui/frontend/src/lib/calculator/calc-model.ts` pure orchestration
+  (forward results + single-target goal-seek + planet build)
+- `ui/frontend/src/lib/calculator/ship-design-area.svelte` reusable
+  design block (5 blocks + 4 techs, override locks, computed-block
+  read-only) — earmarked for the future ship-group upgrade flow
+- `ui/frontend/src/lib/sidebar/calculator-tab.svelte` shell (mode
+  selector, name combobox + Create / Delete, the calc and planet areas
+  inline)
+- `ui/frontend/src/map/reach-circles.ts` + `lib/calculator/reach.svelte.ts`
+  shared store: the calculator publishes the selected planet origin and
+  loaded speed, the map draws 1–3 reach circles
+- `lib/calculator/load-request.svelte.ts` shared store: the table /
+  menus ask the layout to open the calculator on a class
+- topic doc `ui/docs/calculator-ux.md`; `ui/docs/calc-bridge.md`
+  extended with the new wired functions
 
-Dependencies: Phase 18.
+Dependencies: Phases 17, 18, 19/20 (selection store), 29 (map modes).
 
 Acceptance criteria:
 
-- every calculator mode produces results identical to direct
-  `pkg/calc/` calls;
-- inputs persist across view switches per global state-preservation
-  rule;
-- calculator works in history mode against the snapshot's tech levels.
+- every result is byte-identical to direct `pkg/calc/` calls on shared
+  fixtures (Go parity tests);
+- locking one result back-solves its claimed input; a second lock is
+  disabled; an unreachable target shows the error state;
+- Create reuses the existing ship-class command flow and validator;
+  selecting an existing class loads it as a template;
+- inputs persist across view switches per the global state-preservation
+  rule; the calculator works in history mode against the snapshot's
+  tech levels;
+- selecting an own planet draws the reach circles; clearing the
+  selection or an invalid design removes them;
+- the standalone designer view/route no longer exists.
 
 Targeted tests:
 
-- Vitest snapshot tests per mode on canonical inputs;
-- Playwright e2e: switch modes, confirm input persistence.
+- Go: `pkg/calc` unit tests + engine parity (`ProduceShip`,
+  `BombingPower`); `ui/core/calc` bridge parity; solver round-trips;
+- Vitest: `calc-model` (forward, goal-seek per claim, infeasible),
+  `calculator-tab` (results, goal-seek, Create, planet area),
+  `reach-circles` math;
+- Playwright e2e: create / list / delete via the table + calculator,
+  Create-disabled-while-invalid (`tests/e2e/ship-classes.spec.ts`).
+
+Note: the WASM artefact `ui/frontend/static/core.wasm` must be rebuilt
+(`make wasm`, needs TinyGo) for the new bridge functions to be present
+at runtime and in the Playwright suite; Vitest injects a fake `Core`
+and does not need the rebuild.
 
 ## Phase 31. Wails Desktop Wrapper
 
@@ -3483,54 +3543,56 @@ Targeted tests:
 - regression test: bumping the app version invalidates the prior
   service worker.
 
-## Phase 34. Multi-Turn Projection — Single-Turn Forecast and Range Circles
+## Phase 34. Multi-Turn Projection — Realistic Planet Forecast
 
 Status: pending. Long-term scope deferred but this phase ships real
 features.
 
-Goal: ship two concrete projection features (planet next-turn
-forecast and ship-designer reach circles) plus the transient
-map-overlay back-stack mechanism that the reach-circles feature is
-the first user of.
+Goal: ship a realistic multi-turn planet projection and surface it in
+the planet inspector and in the calculator's planet area. Reach circles
+already shipped in Phase 30 (auto-drawn from the calculator's selected
+planet); this phase no longer owns them.
+
+The Phase 30 planet area is single-turn (MAT-only): it answers "ships
+this turn / turns per ship" at the current or overridden MAT. This phase
+makes it realistic and multi-turn by extracting the planet economy into
+`pkg/calc` and simulating turns: population growth (`×1.08`), material /
+capital / colonist supply, and the capital/colonist unpacking that
+mirrors `MakeTurn` steps 09/12/14/15. CAP and COL only affect future
+turns (post-production unpacking), so they become meaningful here and
+are added to the calculator's planet area as supply inputs alongside
+MAT.
 
 Artifacts:
 
-- `ui/frontend/src/lib/projection/` minimal projection engine that
-  computes one-turn-ahead state for a single planet using `pkg/calc/`
-- planet inspector forecast section showing next-turn population,
-  industry, materials stockpile, and production progress
-- `ui/frontend/src/lib/navigation/transient-overlay.ts` push/pop
-  back-stack mechanism for map overlays driven by other views, with
-  a back-button affordance on the map that returns to the originating
-  view with state preserved
-- ship-designer `Preview range on map` action that pushes a transient
-  overlay onto the map showing concentric reach circles for 1, 2, 3,
-  4 turns from a chosen origin, computed from the in-progress ship
-  design and the player's current Drive tech via `ui/core/calc/`
-- topic doc `ui/docs/multi-turn-projection.md` describing the
-  long-term vision (multi-turn planning mode, scenario branches) and
-  the phased path to it
+- `pkg/calc/` planet-economy extraction (single-sourced, engine
+  delegates): `PlanetProduction`, `ProducePopulation`,
+  `UnpackColonists`, `UnpackCapital`, reusing `ProduceShipsInTurn`; a
+  multi-turn projector `ProjectPlanetBuild` answering "K ships in M
+  turns" under guaranteed per-turn supply
+- thin bridges in `ui/core/calc/` + `Core` typings
+- planet inspector forecast section (next-turn population, industry,
+  materials, production progress)
+- calculator planet area gains CAP and COL supply inputs and switches
+  its readout to the multi-turn projector
+- topic doc `ui/docs/multi-turn-projection.md` (long-term vision:
+  multi-turn planning mode, scenario branches)
 
-Dependencies: Phases 17, 18.
+Dependencies: Phases 17, 18, 30.
 
 Acceptance criteria:
 
-- the planet inspector shows a forecast section with next-turn values
-  matching `pkg/calc/` outputs;
-- the ship-designer `Preview range on map` button transitions to the
-  map with reach circles drawn from the chosen origin; back returns
-  to the designer with all in-progress state intact;
-- the transient overlay is cleared if the user navigates to any other
-  view via the header dropdown.
+- projector output is byte-identical to running the engine's per-turn
+  planet update over the same turns (Go parity);
+- the planet inspector shows a forecast section matching it;
+- the calculator planet area honours MAT / CAP / COL supply and shows
+  "K ships in M turns" consistent with the projector.
 
 Targeted tests:
 
-- Vitest unit tests for the projection engine on canonical fixtures;
-- Vitest unit tests for the transient-overlay push/pop logic and
-  state preservation;
-- Playwright e2e: open a planet inspector, observe one-turn forecast;
-  open a ship designer, click `Preview range on map`, see reach
-  circles, click back, return with state intact.
+- Go parity tests for each extracted economy formula and the projector;
+- Vitest for the calculator planet area with supply inputs;
+- Playwright e2e: planet inspector forecast section.
 
 ## Phase 35. Polish — Accessibility, Localisation, Error UX