feat(native): add WGC hardware H264 source (#109)

Adds the explicit Windows WGC/D3D11 hardware-only Media Foundation H.264 source, process-tree audio, direct Go/Pion fanout, source-aware UI/gate, and unique evaluation package helper. Browser VP8 remains the default. Local acceptance and bounded real-device evidence are recorded in the PR; GitHub jobs were billing-blocked before executing any step.

.github/workflows/native-sender-package.yml

@@ -5,7 +5,7 @@ on:
   pull_request:
     paths:
       - "native/sender/**"
-      - "native/process-audio-helper/**"
+      - "native/window-capture-helper/**"
       - "scripts/package-native-sender.ps1"
       - ".github/workflows/native-sender-package.yml"
   push:
@@ -13,7 +13,7 @@ on:
       - main
     paths:
       - "native/sender/**"
-      - "native/process-audio-helper/**"
+      - "native/window-capture-helper/**"
       - "scripts/package-native-sender.ps1"
       - ".github/workflows/native-sender-package.yml"