UI: tab-bar navigation — drop the hamburger

Replace Menu.svelte (hamburger) everywhere with tab-bar navigation:
- Settings hub (SettingsHub) from the lobby ⚙️ tab: Settings/Profile/
  Friends/About as in-place tabs, back → lobby; the lobby ⚙️ badge counts
  incoming friend requests (invitations keep their own lobby section).
- Comms hub (CommsHub) from the move-history 💬: Chat/Dictionary tabs,
  back → game; Dictionary only while the game is active.
- Game menu items relocate into the open history: 🏁 leave / 📤 export in
  the header, 🤝 add-friend per opponent card, 💬 comms; unread chat is
  badged on the score bar + the 💬.
- TapConfirm (tap → fading ✅ → tap) replaces the Skip/Hint press-and-hold
  popovers and drives the add-friend confirm.
- Fix the move-history "jump": the slid board is inert and the stage can't
  scroll, so a swipe up genuinely closes the history.

Remove Menu.svelte + HoldConfirm.svelte. Docs: UI_DESIGN, FUNCTIONAL(+ru),
PRERELEASE. UI check/unit/build/bundle/e2e (Chromium+WebKit) all green.

ui/src/lib/i18n/en.ts

@@ -63,7 +63,6 @@ export const en = {
   'game.skip': 'Skip',
   'game.shuffle': 'Shuffle',
   'game.hint': 'Hint',
-  'game.history': 'History',
   'game.chat': 'Chat',
   'game.checkWord': 'Check word',
   'game.dropGame': 'Drop game',
@@ -83,7 +82,6 @@ export const en = {
   'game.wordIllegal': '“{word}” is not valid',
   'game.complain': 'Disagree',
   'game.complaintSent': 'Thanks, sent for review.',
-  'game.confirm': 'Ok',
   'game.check': 'Check',
   'game.checkWait': 'Please wait a moment.',
   'game.noHintOptions': 'No options with your letters.',
@@ -242,8 +240,7 @@ export const en = {
 
   'game.exportGcg': 'Export GCG',
   'game.gcgActiveOnly': 'Available once the game is finished.',
-  'game.requestSent': 'Request sent',
-  'game.alreadyFriends': '✓ In friends',
+  'game.addFriendShort': 'Add friend?',
 
   'time.minutes': '{n} min',
   'time.hours': '{n} h',