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/lib/i18n.test.ts

@@ -9,8 +9,8 @@ describe('i18n catalog', () => {
   });
 
   it('interpolates parameters', () => {
-    expect(translate('en', 'game.bag', { n: 7 })).toBe('Bag 7');
-    expect(translate('ru', 'game.bag', { n: 7 })).toBe('Мешок 7');
+    expect(translate('en', 'game.bag', { n: 7 })).toBe('7 in the bag');
+    expect(translate('ru', 'game.bag', { n: 7 })).toBe('7 в мешке');
   });
 
   it('maps error codes to keys with a generic fallback', () => {