v3.1.0: Invite-gated auth, Glicko-2 ratings, matchmaking queue

- Enforce invite codes on registration (INVITE_ONLY=true by default)
- Bootstrap admin account for first-time setup
- Require authentication for WebSocket connections and room creation
- Add Glicko-2 rating system with multiplayer pairwise comparisons
- Add Redis-backed matchmaking queue with expanding rating window
- Auto-start matched games with standard rules after countdown
- Add "Find Game" button and matchmaking UI to client
- Add rating column to leaderboard
- Scale down docker-compose.prod.yml for 512MB droplet

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/timing-config.js

@@ -128,6 +128,18 @@ const TIMING = {
         pulseDelay: 200,        // Delay before card appears (pulse visible first)
     },
 
+    // V3_17: Knock notification
+    knock: {
+        statusDuration: 2500,       // How long the knock status message persists
+    },
+
+    // V3_17: Scoresheet modal
+    scoresheet: {
+        playerStagger: 150,         // Delay between player row animations
+        columnStagger: 80,          // Delay between column animations within a row
+        pairGlowDelay: 200,        // Delay before paired columns glow
+    },
+
     // Player swap animation steps - smooth continuous motion
     playerSwap: {
         flipToReveal: 400,      // Initial flip to show card