fix: eliminate voice ducking caused by rogue LiveKit audio elements

Add MutationObserver to neutralize LiveKit's re-attached <audio> elements,
mark our keep-alive elements with data-opencord, detach tracks on unsubscribe,
remove dangerous blanket .play(), and soften compressor to transparent limiter.

packages/web/src/audio/AudioManager.ts

@@ -6,6 +6,7 @@ export class AudioManager {
   private inputDestination: MediaStreamAudioDestinationNode | null = null;
   private silentGain: GainNode | null = null;
   private analyser: AnalyserNode | null = null;
+  private masterCompressor: DynamicsCompressorNode | null = null;
   
   private currentInputDeviceId: string = 'default';
   private currentStream: MediaStream | null = null;
@@ -35,7 +36,17 @@ export class AudioManager {
     
     this.silentGain = this.ctx.createGain();
     this.silentGain.gain.value = 0;
-    
+
+    // Master compressor/limiter — prevents clipping when multiple
+    // audio sources (voice + stream) sum at the output.
+    this.masterCompressor = this.ctx.createDynamicsCompressor();
+    this.masterCompressor.threshold.value = -1;    // only engage near digital clipping
+    this.masterCompressor.knee.value = 0.5;        // hard knee — transparent below threshold
+    this.masterCompressor.ratio.value = 4;         // gentle limiting, no ducking
+    this.masterCompressor.attack.value = 0.0005;   // 0.5ms — catch transient peaks
+    this.masterCompressor.release.value = 0.01;    // 10ms — recover quickly
+    this.masterCompressor.connect(this.ctx.destination);
+
     this.inputGain.connect(this.inputDestination);
     this.inputGain.connect(this.analyser);
     this.inputGain.connect(this.silentGain);
@@ -107,8 +118,8 @@ export class AudioManager {
     gainNode.gain.value = options.volume ?? 0.5;
 
     source.connect(gainNode);
-    gainNode.connect(this.ctx.destination);
-    
+    gainNode.connect(this.masterCompressor!);
+
     source.start(0);
     return source;
   }
@@ -178,6 +189,30 @@ export class AudioManager {
     return this.analyser!;
   }
 
+  /**
+   * Ensures the AudioContext exists and returns it.
+   * Unlike getContext(), this will never return null — it lazily
+   * creates the context if it hasn't been initialised yet.
+   * The context may be in 'suspended' state but Web Audio nodes
+   * can be created and connected regardless; audio will flow
+   * once the context resumes.
+   */
+  ensureContext(): AudioContext {
+    if (!this.ctx) this.initContext();
+    return this.ctx!;
+  }
+
+  /**
+   * Returns the master output bus (DynamicsCompressorNode).
+   * All remote audio (voice, stream) should connect their GainNodes
+   * to this node instead of directly to ctx.destination. The compressor
+   * prevents clipping when multiple sources sum together.
+   */
+  getMasterOutput(): AudioNode {
+    if (!this.ctx) this.initContext();
+    return this.masterCompressor!;
+  }
+
   getContext(): AudioContext | null {
     return this.ctx;
   }