Audio render-hook M4: audio panel source indicator + stream-count debug view

Surfaces the render-hook diagnostics in the Audio panel.

- HookStatusView / IpcServer::hook_status(): carry audio_streams_seen +
  audio_streams[] from the hook's back-channel.
- InjectionPanel: expose hook_status() so the audio panel can read the counts.
- AudioPanel::draw_ui(HookStatusView): show the active Source (green Hooked
  vs amber Loopback); only warn about the local echo on the loopback path. Add
  the required render-stream table: one row per stream with format, cumulative
  frames, the primary tagged, and a live/idle dot derived from frame-count
  deltas. Notes overflow when the game exceeds kMaxAudioStreams slots.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

host/src/ipc/ipc_server.cpp

@@ -66,6 +66,11 @@ HookStatusView IpcServer::hook_status() const
 	view.raw_input_gamepad = s.raw_input_gamepad != 0;
 	view.raw_input_gamepad_sink = s.raw_input_gamepad_sink != 0;
 	view.dinput_loaded = s.dinput_loaded != 0;
+	view.audio_streams_seen = s.audio_streams_seen;
+	for (std::uint32_t i = 0; i < kMaxAudioStreams; ++i)
+	{
+		view.audio_streams[i] = s.audio_streams[i];
+	}
 	return view;
 }