Live streaming tech selection (#24374)

* allow users to select live streaming technology

* fix webrtc being downgraded to mse on load

`useUserPersistence` seeds state with the default and loads asynchronously, so the first render always used `mse` instead of the saved choice, and `useWebRTCGloballyAvailable` reports `checking` until the probe settles and re-enters that state on every consumer mount, so a saved `webrtc` was rewritten to `mse` even after the probe had already passed. On Safari the MSE player then timed out and latched the jsmpeg fallback. A pending probe now counts as available, the player waits on `autoLive` until the stored preferences load, and `handleError` gates on the mode in use since the fallback flag no longer implies webrtc is untried. A rejected IndexedDB read also resolves `loaded` now, so a blocked store can't leave the player waiting forever.

* add support for configurable ICE servers in WebRTC player

* add mic error state, fix dialog overwriting saved choice and dashboard ignoring stream

* tweaks

web/src/hooks/use-user-persistence.ts

@@ -185,7 +185,12 @@ export function useUserPersistence<S>(
       setLoaded(true);
     }
 
-    loadWithMigration();
+    // Consumers gate on this flag and the state already holds the defaults,
+    // so a rejected read must still resolve to "loaded".
+    loadWithMigration().catch(() => {
+      loadedKeyRef.current = namespacedKey;
+      setLoaded(true);
+    });
   }, [
     auth.isLoading,
     isAuthenticated,