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.

ui/e2e/quickmatch.spec.ts

@@ -75,7 +75,7 @@ test('AI game: after it ends, no GCG export and no comms entry', async ({ page }
   await page.locator('.scoreboard').click();
   await page.getByRole('button', { name: 'Drop game' }).click();
   await page.locator('button.danger').click();
-  await expect(page.locator('.status .over')).toBeVisible();
+  await expect(page.locator('.turnstrip.result')).toBeVisible();
 
   // Reopen the history (resigning auto-closed it): the finished AI game offers no GCG export and
   // no comms entry at all.