feat(ui): per-kind active-game limit lock on the New Game screen

Carry the caller's per-tier active-game caps and each game's kind on the
wire (Profile.game_limits + GameView.kind, additive FBS + gateway transcode
+ client codec, committed regen). The New Game screen counts the player's
active games per kind from the lobby and locks a capped start: an outline
button with a lock that opens a funnel modal instead of a game -- a sign-in
prompt for a guest, a "finish a current game first" notice for a signed-in
account (native Telegram popup, in-app modal elsewhere). The lock lifts via
the existing profile refetch after a guest->durable upgrade.

Remove the lobby's old at_game_limit New-Game tab disable + notice: the flag
(now the random-kind cap) conflicted with the per-kind lock -- it hid the
screen where the lock lives and wrongly blocked an unfulfilled kind. The New
Game tab is always enabled; the per-kind start lock is the only gate. The
at_game_limit wire field stays (unused by the client) for a later cleanup.

Tests: client lock logic + codec kind/game_limits roundtrip + gateway
transcode encode + native popup builders (unit); a mock e2e for the lock
badge and the modal.

ui/src/lib/i18n/en.ts

@@ -379,6 +379,11 @@ export const en = {
   'new.multipleWordsPerTurn': 'Multiple words per turn',
   'new.start': 'Start game',
   'new.invited': 'Invitation sent.',
+  'new.limitGuestTitle': 'More games?',
+  'new.limitGuestBody': 'Sign in or create an account to play several games at once.',
+  'new.limitDurableTitle': 'Game limit',
+  'new.limitDurableBody': 'You have reached the limit of simultaneous games — finish a current one first.',
+  'new.limitLogin': 'Sign in',
   'new.noFriends': 'Add friends first to invite them.',
   'new.opponentAI': 'AI',
   'new.opponentRandom': 'Random player',