🐛(frontend) gate blur on WebGL2 transformer support

`ProcessorWrapper.isSupported` reports pipeline support but not
whether the WebGL2 transformer is available. On browsers where it
is not (e.g. Chrome/Edge on Windows with WebGL2 disabled by a GPU
blocklist), toggling blur throws at runtime.

Update `supportsBackgroundProcessors()` to check both, so the UI
only exposes blur when it can actually run.

fix 019f8e3b-f035-73e2-9d6a-d0dd2d0a1163

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

@@ -1,4 +1,7 @@
-import { ProcessorWrapper } from '@livekit/track-processors'
+import {
+  ProcessorWrapper,
+  supportsBackgroundProcessors,
+} from '@livekit/track-processors'
 import type { Track, TrackProcessor } from 'livekit-client'
 import { BackgroundCustomProcessor } from './BackgroundCustomProcessor'
 import { UnifiedBackgroundTrackProcessor } from './UnifiedBackgroundTrackProcessor'
@@ -34,7 +37,9 @@ export class BackgroundProcessorFactory {
   }
 
   static isSupported() {
-    return ProcessorWrapper.isSupported || BackgroundCustomProcessor.isSupported
+    return (
+      supportsBackgroundProcessors() || BackgroundCustomProcessor.isSupported
+    )
   }
 
   static getProcessor(
@@ -45,7 +50,7 @@ export class BackgroundProcessorFactory {
 
     if (!isBlur && !isVirtual) return undefined
 
-    if (ProcessorWrapper.isSupported) {
+    if (supportsBackgroundProcessors()) {
       return new UnifiedBackgroundTrackProcessor(config)
     }