fix: revert E2E AEAD wrapping (broke multi-client voice); add Android CAMERA

Voice regression: EncryptingTransport encrypts media with the pairwise
client↔relay session key, but the relay forwards bytes without re-encrypting
per recipient. Sender's key_A ≠ recipient's key_B → recipient cannot decrypt
→ silent audio between mac and android. Drop the wrapper; restore plaintext-
over-QUIC-TLS to the relay. Proper E2E needs MLS group keys or relay hop-by-
hop re-encryption (future PRD).

Android camera: add CAMERA manifest permission + runtime request via
MainActivity. NOTE: still not sufficient — Tauri/Wry's WebChromeClient does
not grant getUserMedia, so video on Android needs a Tauri plugin override
or native Camera2 path. Documented in MainActivity.kt.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

desktop/src-tauri/gen/android/app/src/main/AndroidManifest.xml

@@ -3,7 +3,9 @@
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.RECORD_AUDIO" />
     <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
+    <uses-permission android:name="android.permission.CAMERA" />
     <uses-feature android:name="android.hardware.microphone" android:required="true" />
+    <uses-feature android:name="android.hardware.camera" android:required="false" />
 
     <!-- AndroidTV support -->
     <uses-feature android:name="android.software.leanback" android:required="false" />

desktop/src-tauri/gen/android/app/src/main/java/com/wzp/desktop/MainActivity.kt

@@ -16,10 +16,19 @@ class MainActivity : TauriActivity() {
     private const val AUDIO_PERMISSIONS_REQUEST = 4242
     private val REQUIRED_AUDIO_PERMISSIONS = arrayOf(
       Manifest.permission.RECORD_AUDIO,
-      Manifest.permission.MODIFY_AUDIO_SETTINGS
+      Manifest.permission.MODIFY_AUDIO_SETTINGS,
+      Manifest.permission.CAMERA
     )
   }
 
+  // NOTE: granting CAMERA at the Android system layer is necessary but NOT
+  // sufficient for video on Android. Tauri/Wry's internal WebChromeClient
+  // does not currently grant `getUserMedia` permission requests, so the
+  // browser-layer getUserMedia call still fails even after the OS grants
+  // CAMERA. Fixing this needs either a Tauri plugin that overrides the
+  // WebChromeClient, or a native Camera2/CameraX capture path that bypasses
+  // the WebView. Tracked as a follow-up.
+
   override fun onCreate(savedInstanceState: Bundle?) {
     enableEdgeToEdge()
     super.onCreate(savedInstanceState)