ui/phase-16: pick any planet in reach + stronger pick-mode dim

The cargo-route picker filtered out unidentified planets, so an
early-game player who had spotted but not surveyed a destination
could not configure a route to it — the engine has no such
restriction (`game/internal/controller/route.go.PlanetRouteSet`
only checks ownership of the origin and `util.ShortDistance(...) <=
FligthDistance`). Drop the unidentified guard and document the
contract in `cargo-routes-ux.md` plus a comment over `reachableSet()`.

Pick-mode dim now drops both alpha and tint on out-of-reach
planets so bright shapes (`STYLE_LOCAL` is `0x6dd2ff`) collapse
into a single muted gray. The single-channel `dimAlpha=0.3` was too
gentle against the dark theme — the user reported the dim wasn't
visible. Tighten to `dimAlpha=0.35 + dimTint=0x303841`; restore
both on tear-down.

Also threads through the user's `pkg/calc/race.go.FligthDistance`
addition: `calc-bridge.md` records the new Go-side reference (the
engine's `Race.FlightDistance()` already wraps it), and the picker
comment points at the canonical formula location.

Tests:
- `inspector-planet-cargo-routes.test.ts` adds two cases — a
  reach-spans-every-kind case (own + foreign + uninhabited +
  unidentified all picked when in range) and a successful pick to
  an unidentified destination.
- All 356 vitest cases + chromium-desktop / webkit-desktop e2e
  cargo-routes pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ui/docs/cargo-routes-ux.md

@@ -123,11 +123,20 @@ localPlayerDrive`. The local player's drive comes from the report's
 `Player` block, looked up by `name === report.race`
 (`api/game-state.ts.findLocalPlayerDrive`).
 
+The Go-side counterpart is `pkg/calc/race.go.FligthDistance`. The
+engine accepts a route from a player-owned planet to **any** planet
+inside that distance — own, foreign-race, uninhabited, or
+unidentified all qualify
+(`game/internal/controller/route.go.PlanetRouteSet` only enforces
+ownership of the *origin*). The picker mirrors that contract: the
+`reachableSet()` in `cargo-routes.svelte` filters out only the
+source planet itself.
+
 Why inline rather than via a Go calc bridge? See the Phase 15 / 16
 deferral note in [`calc-bridge.md`](./calc-bridge.md). The formula
 is trivial (`tech × 40`) and the WASM glue would be premature
 infrastructure; when the calc bridge phase lands the shared
-`pkg/calc.Reach` will replace this implementation.
+`pkg/calc.FligthDistance` will replace this implementation.
 
 ## Tests