feat(recording): add output format options and MP4 conversion support

- Introduced `outputFormat` state in `WccRecordingPanel` for selecting between MP4 and WebM formats.
- Updated `RecorderService` to handle MP4 conversion using mediabunny.
- Added type stubs for `MediaStreamAudioTrack` and `MediaStreamVideoTrack` to ensure type safety.
- Updated documentation to reflect changes in output format handling.

ts_web/types/dom-mediacapture-stub/index.d.ts

@@ -0,0 +1,12 @@
+// Minimal type stubs for MediaCapture Transform API types not yet in lib.dom.d.ts.
+// These specialize MediaStreamTrack for audio/video so mediabunny's API is type-safe.
+
+interface MediaStreamAudioTrack extends MediaStreamTrack {
+  readonly kind: 'audio';
+  clone(): MediaStreamAudioTrack;
+}
+
+interface MediaStreamVideoTrack extends MediaStreamTrack {
+  readonly kind: 'video';
+  clone(): MediaStreamVideoTrack;
+}

ts_web/types/dom-mediacapture-stub/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "@types/dom-mediacapture-transform",
+  "version": "0.0.0",
+  "description": "Minimal stub providing MediaStreamVideoTrack/MediaStreamAudioTrack for TS 6",
+  "types": "index.d.ts"
+}

ts_web/types/dom-webcodecs-stub/index.d.ts

@@ -0,0 +1,2 @@
+// Empty stub: TypeScript 6 includes WebCodecs types in lib.dom.d.ts natively.
+// This prevents @types/dom-webcodecs from conflicting with the built-in types.

ts_web/types/dom-webcodecs-stub/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "@types/dom-webcodecs",
+  "version": "0.0.0",
+  "description": "Empty stub — TypeScript 6 provides WebCodecs types natively in lib.dom.d.ts",
+  "types": "index.d.ts"
+}