feat(online): live queue count — friends see each other waiting

The server only sent the queue size to the player who just joined, and the
client dropped the count entirely (emitMM ignored s.players). So two friends
queuing together never saw each other, even though the server does seat 2+
waiting humans together within ~25s.

- Server: BroadcastQueueLocked() pushes the current queue size to EVERY waiting
  player on join/cancel (not just the joiner).
- Client: thread the count through emitMM → MatchmakingState.waiting.
- MatchmakingScreen shows "N players in queue" (mm.inQueue) when ≥2 humans wait,
  so friends can tell they're queued together before bots fill the empty seats.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/online/signalr-service.ts

@@ -160,7 +160,7 @@ export class SignalrService implements OnlineService {
       .build();
 
     conn.on("matchmaking", (s: { phase: string; players: number; queuePosition: number | null }) =>
-      this.emitMM(s.phase, s.queuePosition ?? undefined));
+      this.emitMM(s.phase, s.queuePosition ?? undefined, s.players));
     conn.on("matchFound", () => {
       this.emitMM("ready");
       // Safety net: if the initial state never lands (dropped/raced), ask the
@@ -226,7 +226,7 @@ export class SignalrService implements OnlineService {
     }
   }
 
-  private emitMM(phase: string, queuePosition?: number) {
+  private emitMM(phase: string, queuePosition?: number, waiting?: number) {
     const state: MatchmakingState = {
       phase: phase as MatchmakingState["phase"],
       players: [],
@@ -234,6 +234,7 @@ export class SignalrService implements OnlineService {
       ranked: this.mmRanked,
       stake: this.mmStake,
       queuePosition,
+      waiting,
     };
     this.mmCbs.forEach((cb) => cb(state));
   }