🐛(frontend) cache supportsBackgroundProcessors WebGL2 probe result

`supportsBackgroundProcessors()` creates a live WebGL2 context on
every call and never releases it. The method is called from render
paths (e.g. the Effects button on the join screen), so without
caching, each re-render leaks a context until the browser hits its
live-context limit.

This is one of the ways MediaPipe later fails with:

  "emscripten_webgl_create_context() returned error 0"

Support cannot change within a session, so probe once and cache the
result.

CHANGELOG.md

@@ -13,10 +13,6 @@ and this project adheres to
 - ✨(frontend) add 1080p sending resolution option #1660
 - ✨(backend) add Traefik support via configurable media-auth url header #1649
 
-### Changed
-
-- ⬆️(dev) pin LiveKit server to v1.13.6
-
 ### Fixed
 
 - 🐛(frontend) keep the sending resolution picked while the camera is off #1667

compose.yml

@@ -207,7 +207,7 @@ services:
       - kc_postgresql
 
   livekit:
-    image: livekit/livekit-server:v1.13.6
+    image: livekit/livekit-server
     entrypoint: /livekit-server --dev --bind 0.0.0.0 --config ./config.yaml
     ports:
       - "7880:7880"

docker/livekit/Dockerfile

@@ -1,4 +1,4 @@
-FROM livekit/livekit-server:v1.13.6
+FROM livekit/livekit-server:v1.9.4
 
 # We inject the nip.io certificate manually because the livekit chart doesn't support volume mounting
 COPY rootCA.pem /etc/ssl/certs/

src/frontend/src/features/rooms/livekit/components/blur/index.ts

@@ -32,14 +32,18 @@ export interface BackgroundProcessorInterface extends TrackProcessor<Track.Kind>
 }
 
 export class BackgroundProcessorFactory {
+  private static _isSupported?: boolean
+
   static hasModernApiSupport() {
     return ProcessorWrapper.hasModernApiSupport
   }
 
   static isSupported() {
-    return (
+    if (this._isSupported === undefined) {
-      supportsBackgroundProcessors() || BackgroundCustomProcessor.isSupported
+      this._isSupported =
-    )
+        supportsBackgroundProcessors() || BackgroundCustomProcessor.isSupported
+    }
+    return this._isSupported
   }
 
   static getProcessor(