Stage 17 (contour round 4a): quick fixes

- #4 bag label: '{n} in the bag' / 'Bag is empty' (was 'Bag {n}')
- #6 allow a single trailing dot in display names (backend + UI regex + tests)
- #1 double-tap zooms toward the tapped cell, not the top-left
- #8 shuffle fires a short multi-pulse haptic
- #11 highlighted/flashing tiles darken their bottom edge too (shadow joins the flash)
- #13 toast slides up from the bottom and fades out
- #7 hide the logout button (kept wired behind `hidden`)
- #16 admin game seats: left-align numeric columns, clarify the 'Hints used' header

ui/src/game/Game.svelte

@@ -324,6 +324,8 @@
       [r[i], r[j]] = [r[j], r[i]];
     }
     placement = newPlacement(r);
+    // A short "shake": a few quick light taps rather than one.
+    for (let i = 0; i < 4; i++) setTimeout(() => telegramHaptic('light'), i * 55);
   }
   function openExchange() {
     resetPlacement();
@@ -509,13 +511,13 @@
           locale={app.locale}
           {focus}
           oncell={onCell}
-          ontogglezoom={() => { if (!gameOver) zoomed = !zoomed; }}
+          ontogglezoom={(r, c) => { focus = { row: r, col: c }; if (!gameOver) zoomed = !zoomed; }}
         />
       </div>
     </div>
 
     <div class="status">
-      <span>{t('game.bag', { n: view.bagLen })}</span>
+      <span>{view.bagLen === 0 ? t('game.bagEmpty') : t('game.bag', { n: view.bagLen })}</span>
       {#if gameOver}
         <strong class="over">{t('game.over')} — {resultText()}</strong>
       {:else}