Add managed UIKit iOS client

docs/roadmap.md

@@ -85,13 +85,14 @@ exists from M1 so the protocol can be exercised long before any GUI.
   deployment target.
 - AVAudioSession not needed on macOS (CoreAudio via the core directly).
 
-**iOS (Swift/SwiftUI) — pending:**
-- SwiftUI app consuming the same `VoiceCatCore` package.
+**iOS (.NET/UIKit) — replacement in progress 2026-09-19:**
+- Native C# UIKit app consuming `VoiceCat.Core`; UIKit was chosen over MAUI for direct audio
+  lifecycle control and the strongest VoiceOver surface.
 - ~~AVAudioSession, mic permission, foreground voice.~~ ✓ Done — `IOSAudioRouter` drives
   all iOS audio routing (input ports, orientation/polar patterns, HFP/A2DP, Standard/Raw
   mic mode, stereo capture), `vc_audio_suspend`/`vc_audio_resume` for interruptions.
-- ReplayKit broadcast extension for `SCREEN_AUDIO` — feeds `CMSampleBuffer` audio via
-  `vc_stream_feed_pcm` (see architecture.md §4).
+- The small Swift ReplayKit broadcast extension remains and writes its versioned App Group
+  PCM ring; the C# host drains it into `SCREEN_AUDIO`. See `broadcast-ring-format.md`.
 
 **Exit:** non-technical user installs a client, saves a server, and joins.