Add wake lock toggle to prevent screen sleep on player display

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

src/App.js

@@ -7,7 +7,7 @@ import {
   UserCheck, UserX, HeartCrack, HeartPulse, Zap, EyeOff, ExternalLink, AlertTriangle,
   Play as PlayIcon, Pause as PauseIcon, SkipForward as SkipForwardIcon,
   StopCircle as StopCircleIcon, Users2, Dices, ChevronUp, ChevronDown, ScrollText,
-  Maximize2, Minimize2
+  Maximize2, Minimize2, Moon, Coffee
 } from 'lucide-react';
 
 // Custom CSS for death animation (player view only)
@@ -2311,6 +2311,8 @@ function DisplayView() {
   const [campaignBackgroundUrl, setCampaignBackgroundUrl] = useState('');
   const [isPlayerDisplayActive, setIsPlayerDisplayActive] = useState(false);
   const [isFullscreen, setIsFullscreen] = useState(false);
+  const [wakeLockEnabled, setWakeLockEnabled] = useState(false);
+  const wakeLockRef = useRef(null);
   const currentParticipantRef = useRef(null);
 
   useEffect(() => {
@@ -2327,6 +2329,33 @@ function DisplayView() {
     }
   };
 
+  useEffect(() => {
+    if (!wakeLockEnabled) {
+      wakeLockRef.current?.release();
+      wakeLockRef.current = null;
+      return;
+    }
+
+    const acquire = async () => {
+      try {
+        wakeLockRef.current = await navigator.wakeLock.request('screen');
+      } catch (e) {
+        console.error('Wake lock failed:', e);
+      }
+    };
+
+    acquire();
+
+    // Re-acquire after tab becomes visible again (browser auto-releases on hide)
+    const onVisChange = () => { if (document.visibilityState === 'visible') acquire(); };
+    document.addEventListener('visibilitychange', onVisChange);
+    return () => {
+      document.removeEventListener('visibilitychange', onVisChange);
+      wakeLockRef.current?.release();
+      wakeLockRef.current = null;
+    };
+  }, [wakeLockEnabled]);
+
   useEffect(() => {
     if (!db) {
       setEncounterError("Firestore not available.");
@@ -2450,13 +2479,22 @@ function DisplayView() {
       className={`p-4 md:p-8 rounded-xl shadow-2xl ${!campaignBackgroundUrl ? 'bg-stone-950' : ''}`}
       style={displayStyles}
     >
+      <div className="fixed top-3 right-3 z-50 flex gap-2">
+        <button
+          onClick={() => setWakeLockEnabled(v => !v)}
+          title={wakeLockEnabled ? 'Allow sleep' : 'Prevent sleep'}
+          className={`p-2 rounded-lg transition-all ${wakeLockEnabled ? 'bg-amber-600 hover:bg-amber-700 text-white' : 'bg-stone-800 bg-opacity-80 hover:bg-opacity-100 text-stone-300 hover:text-white'}`}
+        >
+          {wakeLockEnabled ? <Coffee size={20} /> : <Moon size={20} />}
+        </button>
         <button
           onClick={toggleFullscreen}
           title={isFullscreen ? 'Exit fullscreen' : 'Enter fullscreen'}
-        className="fixed top-3 right-3 z-50 bg-stone-800 bg-opacity-80 hover:bg-opacity-100 text-stone-300 hover:text-white p-2 rounded-lg transition-all"
+          className="bg-stone-800 bg-opacity-80 hover:bg-opacity-100 text-stone-300 hover:text-white p-2 rounded-lg transition-all"
         >
           {isFullscreen ? <Minimize2 size={20} /> : <Maximize2 size={20} />}
         </button>
+      </div>
       <div className={campaignBackgroundUrl ? 'bg-stone-950 bg-opacity-75 p-4 md:p-6 rounded-lg' : ''}>
         <h2 className="text-4xl md:text-5xl font-bold text-center text-amber-400 mb-2 font-cinzel tracking-wide">{name}</h2>