fix(calls): resolve EC mute hang, robust camera focus, PiP NaN guard (N122/N123/N126)

- N122: setMediaState resolves on EC's transport ACK instead of waiting for a
  DeviceMute state-echo that EC may elide or skip during teardown — which
  previously stranded the promise forever and silently skipped the initial
  deafen state + first StateUpdate on join. Dropped the single-slot
  mediaStatePromiseResolver; onMediaState remains the authoritative sync path.
- N123: focusCameraParticipant now waits for a spotlight videoTile to mount via
  a MutationObserver (with a 600ms hard-timeout fallback) instead of a fixed
  2-frame delay that EC's React commit can exceed on slower devices.
- N126: PiP position restored from localStorage is shape+finiteness validated,
  so corrupt data can't feed NaN into the position math (invalid 'NaNpx' CSS).

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

src/app/components/CallEmbedProvider.tsx

@@ -720,7 +720,25 @@ export function CallEmbedProvider({ children }: CallEmbedProviderProps) {
     if (pipMode) {
       if (!wasInPip) {
         const saved = localStorage.getItem('pip-position');
-        const savedPos = saved ? (JSON.parse(saved) as { left: number; top: number }) : null;
+        let savedPos: { left: number; top: number } | null = null;
+        if (saved) {
+          try {
+            const raw = JSON.parse(saved) as { left?: unknown; top?: unknown };
+            // Validate shape + finiteness: a corrupt value would otherwise feed
+            // NaN into Math.min and produce an invalid `NaNpx` CSS value.
+            if (
+              raw &&
+              typeof raw.left === 'number' &&
+              Number.isFinite(raw.left) &&
+              typeof raw.top === 'number' &&
+              Number.isFinite(raw.top)
+            ) {
+              savedPos = { left: raw.left, top: raw.top };
+            }
+          } catch {
+            savedPos = null;
+          }
+        }
         el.style.right = 'auto';
         el.style.bottom = 'auto';
         if (savedPos) {

src/app/plugins/call/CallControl.ts

@@ -20,8 +20,6 @@ export class CallControl extends EventEmitter implements CallControlState {
 
   private _pipMode = false;
 
-  private mediaStatePromiseResolver: undefined | (() => void);
-
   private get document(): Document | undefined {
     return this.iframe.contentDocument ?? this.iframe.contentWindow?.document;
   }
@@ -183,13 +181,13 @@ export class CallControl extends EventEmitter implements CallControlState {
   }
 
   private async setMediaState(state: ElementMediaStatePayload) {
-    const data = await this.call.transport.send(ElementWidgetActions.DeviceMute, state);
-    return new Promise<typeof data>((resolve) => {
-      if (this.mediaStatePromiseResolver) {
-        this.mediaStatePromiseResolver();
-      }
-      this.mediaStatePromiseResolver = () => resolve(data);
-    });
+    // transport.send resolves once EC has ACK'd the command, which is enough to
+    // consider the mute applied. We deliberately do NOT gate completion on a
+    // follow-up DeviceMute state-echo: EC may elide it (e.g. when the requested
+    // state already matches its current state) or skip it during teardown,
+    // which would strand this promise forever and block applyState(). The echo,
+    // when it does arrive, is still handled authoritatively by onMediaState().
+    return this.call.transport.send(ElementWidgetActions.DeviceMute, state);
   }
 
   private setSound(sound: boolean): void {
@@ -233,11 +231,6 @@ export class CallControl extends EventEmitter implements CallControlState {
     if (this.microphone && !this.sound) {
       this.toggleSound();
     }
-
-    if (this.mediaStatePromiseResolver) {
-      this.mediaStatePromiseResolver();
-      this.mediaStatePromiseResolver = undefined;
-    }
   }
 
   private onControlMutation() {
@@ -394,10 +387,30 @@ export class CallControl extends EventEmitter implements CallControlState {
     }
 
     // Switching to spotlight re-renders EC's layout asynchronously; clicking the
-    // tile in the same tick would land in the old (grid) DOM. Toggle spotlight,
-    // then click on a later frame once the spotlight tiles have mounted.
+    // tile in the same tick would land in the old (grid) DOM. A fixed frame
+    // delay is unreliable (EC's React commit can exceed it on slow devices), so
+    // watch the iframe DOM for a spotlight video tile to mount, then focus —
+    // with a hard timeout so the click is always attempted at least once.
     this.spotlightButton?.click();
-    requestAnimationFrame(() => requestAnimationFrame(applyFocus));
+
+    const tileSelector = '[data-testid="videoTile"]';
+    let settled = false;
+    let observer: MutationObserver | undefined;
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    const finish = () => {
+      if (settled) return;
+      settled = true;
+      if (timer) clearTimeout(timer);
+      observer?.disconnect();
+      applyFocus();
+    };
+    observer = new MutationObserver(() => {
+      if (doc.querySelector(tileSelector)) finish();
+    });
+    observer.observe(doc.body, { childList: true, subtree: true });
+    timer = setTimeout(finish, 600);
+    // A tile may already be present immediately after toggling spotlight.
+    if (doc.querySelector(tileSelector)) finish();
   }
 
   public dispose() {