feat(voice): add WebRTC voice channels with Cloudflare TURN support

Add voice channel functionality with WebRTC peer-to-peer audio:
- Add VoiceSignalingConsumer for WebRTC signaling and peer coordination
- Add GlobalConsumer for real-time presence and voice status updates
- Add voice channel type to Channel model with current_voice_channel tracking on UserProfile
- Add voice controls UI (mute, deafen, disconnect) in status panel
- Add voice member list display in sidebar with avatar support
- Add

chat/urls.py

@@ -14,4 +14,5 @@ urlpatterns = [
     path('admin-panel/', views.admin_panel_view, name='admin_panel'),
     path('message/<int:message_id>/delete/', views.delete_message_view, name='delete_message'),
     path('user/<int:user_id>/block/', views.block_user_view, name='block_user'),
+    path('channel/voice/credentials/', views.voice_credentials_view, name='voice_credentials'),
 ]