fix: QA sprint v1 — 7 issues resolved

Fixes:
- #22 OrbitControls damping: call updateControls() in animate loop
- #23 Empty catch blocks: add console.warn + error surfacing to chat panel
- #24 escapeHtml: add quote escaping (" '), use in renderAgentList
- #25 WS reconnect: check close code (1000/1001) before reconnecting,
  add exponential backoff + heartbeat zombie detection
- #26 IDLE state visibility: brighten from near-invisible to #005500
- #5 PWA: manifest.json, service worker (network-first), theme-color,
  favicon, loading screen, safe-area-inset padding, apple-mobile-web-app
- #14 Adaptive render quality: new quality.js hardware detection (low/
  medium/high tiers), tiered particle counts, grid density, antialias,
  pixel ratio caps

New files:
- js/quality.js — hardware detection + quality tier logic
- manifest.json — PWA manifest
- public/sw.js — service worker (network-first with offline cache)
- public/favicon.svg — SVG favicon
- icons/icon-192.svg, icons/icon-512.svg — PWA icons

js/websocket.js

@@ -10,7 +10,15 @@ let ws = null;
 let connectionState = 'disconnected';
 let jobCount = 0;
 let reconnectTimer = null;
-const RECONNECT_DELAY_MS = 5000;
+let reconnectAttempts = 0;
+
+const RECONNECT_BASE_MS = 2000;
+const RECONNECT_MAX_MS = 30000;
+const HEARTBEAT_INTERVAL_MS = 30000;
+const HEARTBEAT_TIMEOUT_MS = 5000;
+
+let heartbeatTimer = null;
+let heartbeatTimeout = null;
 
 export function initWebSocket(_scene) {
   if (!WS_URL) {
@@ -30,7 +38,9 @@ function connect() {
 
   try {
     ws = new WebSocket(WS_URL);
-  } catch {
+  } catch (err) {
+    console.warn('[Matrix WS] Connection failed:', err.message || err);
+    logEvent('WebSocket connection failed');
     connectionState = 'disconnected';
     scheduleReconnect();
     return;
@@ -38,7 +48,9 @@ function connect() {
 
   ws.onopen = () => {
     connectionState = 'connected';
+    reconnectAttempts = 0;
     clearTimeout(reconnectTimer);
+    startHeartbeat();
     ws.send(JSON.stringify({
       type: 'subscribe',
       channel: 'agents',
@@ -47,27 +59,75 @@ function connect() {
   };
 
   ws.onmessage = (event) => {
+    // Any message counts as a heartbeat response
+    resetHeartbeatTimeout();
     try {
       handleMessage(JSON.parse(event.data));
-    } catch {
+    } catch (err) {
+      console.warn('[Matrix WS] Message parse/handle error:', err.message, '| raw:', event.data?.slice?.(0, 200));
     }
   };
 
-  ws.onerror = () => {
+  ws.onerror = (event) => {
+    console.warn('[Matrix WS] Error event:', event);
     connectionState = 'disconnected';
   };
 
-  ws.onclose = () => {
+  ws.onclose = (event) => {
     connectionState = 'disconnected';
+    stopHeartbeat();
+
+    // Don't reconnect on clean close (1000) or going away (1001)
+    if (event.code === 1000 || event.code === 1001) {
+      console.info('[Matrix WS] Clean close (code ' + event.code + '), not reconnecting');
+      return;
+    }
+
+    console.warn('[Matrix WS] Unexpected close — code:', event.code, 'reason:', event.reason || '(none)');
     scheduleReconnect();
   };
 }
 
 function scheduleReconnect() {
   clearTimeout(reconnectTimer);
-  reconnectTimer = setTimeout(connect, RECONNECT_DELAY_MS);
+  // Exponential backoff: 2s, 4s, 8s, 16s, capped at 30s
+  const delay = Math.min(RECONNECT_BASE_MS * Math.pow(2, reconnectAttempts), RECONNECT_MAX_MS);
+  reconnectAttempts++;
+  console.info('[Matrix WS] Reconnecting in', Math.round(delay / 1000), 's (attempt', reconnectAttempts + ')');
+  reconnectTimer = setTimeout(connect, delay);
 }
 
+/* ── Heartbeat / zombie connection detection ── */
+
+function startHeartbeat() {
+  stopHeartbeat();
+  heartbeatTimer = setInterval(() => {
+    if (ws && ws.readyState === WebSocket.OPEN) {
+      try {
+        ws.send(JSON.stringify({ type: 'ping' }));
+      } catch { /* ignore send failures, onclose will fire */ }
+      heartbeatTimeout = setTimeout(() => {
+        console.warn('[Matrix WS] Heartbeat timeout — closing zombie connection');
+        if (ws) ws.close(4000, 'heartbeat timeout');
+      }, HEARTBEAT_TIMEOUT_MS);
+    }
+  }, HEARTBEAT_INTERVAL_MS);
+}
+
+function stopHeartbeat() {
+  clearInterval(heartbeatTimer);
+  clearTimeout(heartbeatTimeout);
+  heartbeatTimer = null;
+  heartbeatTimeout = null;
+}
+
+function resetHeartbeatTimeout() {
+  clearTimeout(heartbeatTimeout);
+  heartbeatTimeout = null;
+}
+
+/* ── Message handler ── */
+
 function handleMessage(msg) {
   switch (msg.type) {
     case 'agent_state': {
@@ -95,15 +155,17 @@ function handleMessage(msg) {
       }
       break;
     }
+    case 'pong':
     case 'agent_count':
       break;
     default:
+      console.debug('[Matrix WS] Unhandled message type:', msg.type);
       break;
   }
 }
 
 function logEvent(text) {
-  appendChatMessage('SYS', text, colorToCss(0x003300));
+  appendChatMessage('SYS', text, '#005500');
 }
 
 export function getConnectionState() {