Wire client SignalrService to the live .NET backend

- @microsoft/signalr client implementing OnlineService: REST auth, hub
  matchmaking, server-driven game state (onState), play/trump, reactions;
  delegates not-yet-server-backed features (profile/friends/shop/chat/rooms)
  to the mock. Selected via NEXT_PUBLIC_USE_SERVER=1 (NEXT_PUBLIC_SERVER_URL)
- game-store live mode: enterServerMatch + applyServerState (maps server DTO,
  hides opponent hands, tally + SFX), inputs route to the hub; no local engine
- MatchmakingScreen auto-enters the live match when the server signals ready
- Verified end-to-end via scripts/live-test.mjs (auth -> hub -> match -> state)

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

scripts/live-test.mjs

@@ -0,0 +1,42 @@
+// End-to-end smoke test of the live SignalR backend (server must be running).
+import { HubConnectionBuilder, LogLevel } from "@microsoft/signalr";
+
+const SERVER = "http://localhost:5005";
+
+const res = await fetch(`${SERVER}/api/auth/otp/verify`, {
+  method: "POST",
+  headers: { "Content-Type": "application/json" },
+  body: JSON.stringify({ phone: "0912", code: "1234", name: "Tester" }),
+});
+const { token, userId } = await res.json();
+if (!token) throw new Error("no token");
+
+const conn = new HubConnectionBuilder()
+  .withUrl(`${SERVER}/hub/game`, { accessTokenFactory: () => token })
+  .configureLogging(LogLevel.Error)
+  .build();
+
+let matchFound = false;
+let states = 0;
+let sawHand = false;
+let phases = new Set();
+let mySeat = null;
+
+conn.on("matchFound", (m) => { matchFound = true; mySeat = m.seat; });
+conn.on("state", (s) => {
+  states++;
+  phases.add(s.phase);
+  const me = s.players.find((p) => p.seat === s.mySeat);
+  if (me?.hand?.length) sawHand = true;
+});
+
+await conn.start();
+await conn.invoke("StartMatchmaking", { name: "Tester", avatar: "a-fox", level: 3, plan: "pro" });
+await new Promise((r) => setTimeout(r, 7000));
+
+console.log(JSON.stringify({
+  userId, matchFound, mySeat, states, sawHand, phases: [...phases],
+}));
+
+await conn.stop();
+process.exit(0);