Stage 17 round 5 — backend/correctness bug fixes

- Resign on the opponent's turn: engine ResignSeat(seat) resigns a specific seat
  (not just toMove); game.Resign bypasses the turn check and forfeits the actor's seat.
- Quick-match cancel was a UI no-op (only stopped polling): add the full path
  (REST /lobby/cancel -> gateway lobby.cancel -> client) and clear the matchmaker's
  pending result on Cancel, so a cancelled search is dequeued (no 'already queued', no
  later robot-substituted game). NewGame dequeues on cancel and on abandon.
- Lobby win/loss: result.ts ranked by score, so a 0-0 resignation read as a win.
  The winner now takes rank 1 and the viewer is placed from rank 2 — matching the
  game-detail screen.
- Friend request to a robot: robots no longer block requests; the request stays
  pending and expires (friendRequestTTL), mirroring a human who ignores it.
- Nudge cooldown: ErrNudgeTooSoon now maps to a distinct nudge_too_soon code with a
  correct message; the chat nudge button disables during the hourly cooldown; the
  nudge note reads 'Waiting for your move!' (button keeps the Nudge action label).
Tests: engine/service off-turn resign, matchmaker cancel-clears-result, friend-to-robot
inttest, result.ts 0-0 resignation, nudge_too_soon mapping.

ui/src/lib/i18n/en.ts

@@ -94,7 +94,8 @@ export const en = {
 
   'chat.placeholder': 'Quick message…',
   'chat.send': 'Send',
-  'chat.nudge': 'Nudge',
+  'chat.nudge': 'Waiting for your move!',
+  'chat.nudgeAction': 'Nudge',
   'chat.empty': 'No messages yet.',
   'chat.nudged': '{name} nudged you',
 
@@ -155,6 +156,7 @@ export const en = {
   'error.hint_unavailable': 'No hints available.',
   'error.no_hint_available': 'No options with your letters.',
   'error.chat_rejected': 'Message rejected (too long or contains contact info).',
+  'error.nudge_too_soon': "Please don't rush your opponent so often.",
   'error.game_finished': 'This game is finished.',
   'error.not_a_player': 'You are not a player in this game.',
   'error.already_queued': 'You are already in the queue.',