feat(recording): RecordingSession.audio_layout (split when mic on) (FR-SPK)

src-tauri/src/lib.rs

@@ -92,6 +92,10 @@ pub struct RecordingSession {
     /// conditions as `mic_capture`); then attribution falls back to the
     /// voiceprint pass.
     pub mic_activity: Option<Arc<audio::MicActivity>>,
+    /// `audio.wav` channel layout for this recording (FR-SPK): `"split"` (mic
+    /// enabled → stereo mic-left/loopback-right) or `"summed"` (mic off). Passed
+    /// to `finalize_meeting` so playback/diarization/export can branch on it.
+    pub audio_layout: &'static str,
     /// Live notes redesign: raw user-authored notes accumulated *during* the
     /// recording (freeform text + per-moment annotations) — see
     /// `models::ManualNotes`. Mutated by `update_live_notes`/`set_segment_note`