docs(ui): finalize MVP plan structure and de-archaeologize topic docs

MVP web client (Phases 1-30) is complete; reorganize planning + living docs around that.

- PLAN.md kept as the staged MVP record (1-30) with a status block + pointers; removed the 31-36 stages, regression scenarios, and deferred-TODO section (moved out); fixed a stale cross-machine plan path.

- ui/PLAN-finalize.md (new): active web-finalization plan in 8 stages (visual system, a11y, i18n, error UX, PWA, build hygiene, docs, owner manual-QA loop); absorbs former Phases 33 and 35.

- ui/ROADMAP.md (new): post-MVP (Wails, Capacitor, realistic projection, acceptance + regression scenarios) and triaged deferred follow-ups.

- ui/docs/README.md (new): grouped topic-doc index.

- De-archaeologized all 20 ui/docs topic docs + ui/README.md + ui/core/README.md: stripped Phase-N build history, rewritten as current-state; deferred work now points at ROADMAP.md / PLAN-finalize.md. Docs-only; no code change.

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

ui/docs/science-designer-ux.md

@@ -6,9 +6,9 @@ planet's production is set to a science, the planet's industry
 output for that turn is split between the four tech research tracks
 in those proportions
 (`game/internal/controller/planet/production.go.runScienceResearch`).
-Phase 21 lights up the CRUD list, the designer, and the
-production-picker integration. The wire and the engine validation
-are unchanged from earlier phases — only the UI is new.
+The CRUD list, the designer, and the production-picker integration
+are provided by the UI; the wire and engine validation are handled
+by the backend.
 
 ## Engine semantics in one paragraph
 
@@ -41,12 +41,12 @@ from `100`, and the form's Save button stays disabled until the sum
 matches. A live readout under the inputs displays the running total
 so the player can chase it down without trial-and-error guessing.
 
-The strict-sum gate is a Phase 21 decision (alternatives —
-auto-rebalance, raw-parts-with-engine-normalisation — were
-considered and rejected): keeping the input model close to "what
-gets sent on the wire" minimises surprises when the engine returns
-the science exactly as typed. See `lib/util/science-validation.ts`
-for the validator and the conversion helper.
+The strict-sum gate was chosen over alternatives — auto-rebalance
+and raw-parts-with-engine-normalisation — because keeping the input
+model close to "what gets sent on the wire" minimises surprises when
+the engine returns the science exactly as typed. See
+`lib/util/science-validation.ts` for the validator and the
+conversion helper.
 
 ## Name validation