feat(ui): batch of UI polish tweaks

- admin dashboard "Users" count excludes robots (CountUsers, humans only)
- lobby finished-game delete reveal: background matches header/tab-bar (--bg-elev)
- mobile: swipe up on the zoom-out board (no staged tiles) shuffles the rack
- lobby: status icons -25%, game-row top/bottom padding halved
- toast: info tier drifts up ~a tab-bar height while fading over 2s and dismisses
  on tap; error tier unchanged
- game: confirm-move button stays pinned at the right edge; rack tiles shrink to
  fit so a full rack never overflows onto it
- telegram: a successful invite-link redeem shows a welcome window pointing at the bot
- settings: remove the grid-lines toggle; the board is always a gapless checkerboard
- settings/comms hubs: the selected tab highlight wraps icon + label as a pill

Docs: UI_DESIGN (toast, board surface, selected tab), PLAN; e2e updated for the
removed grid-lines toggle.

ui/src/lib/i18n/en.ts

@@ -163,7 +163,6 @@ export const en = {
   'settings.labelsBeginner': 'Beginner',
   'settings.labelsClassic': 'Classic',
   'settings.labelsNone': 'None',
-  'settings.boardLines': 'Grid lines',
   'settings.reduceMotion': 'Reduce motion',
 
   'about.title': 'About',
@@ -241,6 +240,8 @@ export const en = {
   'friends.selfInvite': "Hopefully you've been friends with yourself for a while ☺️",
   'friends.staleInviteTitle': 'Link expired',
   'friends.staleInvite': 'You opened the game from an outdated link. Open the bot {bot} to play and get notifications.',
+  'friends.welcomeRedeemTitle': 'Welcome!',
+  'friends.welcomeRedeem': 'Welcome, {name}!\n\nUse {bot} to join games the most convenient way.',
   'friends.added': 'Added {name}.',
   'friends.blockedList': 'Blocked players',
   'friends.unblock': 'Unblock',