feat(ui): move in-game status to the board — highlight, score badge, full-width rack

Remove the under-board status strip and relocate its signals:
- bag count -> a badge on the exchange/pass control + the foot of the move table
- whose-turn / win-lose -> a thin strip above the score plaques
- the tentative-move caption -> the board itself: staged tiles tint green (legal) or
  pink (illegal), the board tiles a formed word runs through go a shade darker, and an
  orange score badge sits on the main word (digit sized like a tile value, clamped on-board)

The word geometry (covered cells + badge anchor) is a new pure client-side helper
(ui/src/lib/formed.ts), independent of the move evaluator, so it works on the local or
network preview path alike; the badge's number still comes from the preview score.

Rack: a seven-column grid filling the tray width in both layouts — square, full-width
tiles — with the confirm control in the fixed 7th slot.

Settings: a touch-only "Zoom the board" toggle (default on, device-local) gates the
tile-placement auto-zoom; taking a hint while zoomed in now zooms out so the highlighted
hint word is never left off-screen.

Docs (FUNCTIONAL +_ru, UI_DESIGN, ARCHITECTURE) and e2e/unit tests updated.

docs/ARCHITECTURE.md

@@ -435,7 +435,11 @@ Key points:
   through a **session-gated `GET /dict/{variant}/{version}`** edge route
   (immutable; cached in IndexedDB best-effort) and reused across sessions; any
   miss, storage eviction or a bad-connection breaker falls back to the network
-  `evaluate`. The warm-up overlay is `docs/UI_DESIGN.md`.
+  `evaluate`. The warm-up overlay is `docs/UI_DESIGN.md`. The **on-board rendering** of a staged
+  play — the legality tint, the cells a formed word covers, and where the score badge anchors — is a
+  separate **pure geometry helper** (`ui/src/lib/formed.ts`) derived from the board and the staged
+  tiles, so it works regardless of which eval path produced the preview (the badge's number still
+  comes from the preview's score): legality and score stay with the eval, geometry with the board.
 
 ## 6. Game rules