fix(diarization): clear stale speaker rows on reprocess so Participants pane matches (FR-SPK)

Reprocess re-diarizes and upserts the new labels but never deleted the old
ones, so get_meeting (Participants pane) kept returning the discarded run's
labels (e.g. 83) while the transcript showed the new 5. Clear the meeting's
speaker rows before finalize re-inserts the fresh set.

src-tauri/src/commands.rs

@@ -1814,6 +1814,17 @@ pub async fn reprocess_transcript(
     }
     let speakers = speaker_infos_from_segments(&segments, &speaker_names);
 
+    // Drop the previous run's speaker rows before re-inserting the fresh set:
+    // the old labels key to the discarded clustering, so leaving them stranded
+    // in the DB makes the Participants pane show ghosts (e.g. 83 old labels
+    // when the new transcript has 5). finalize_meeting below re-upserts
+    // `speakers`. (FR-SPK)
+    state
+        .store
+        .clear_speakers(&meeting_id)
+        .await
+        .map_err(|e| WaError::new("storage", e.to_string()))?;
+
     let duration_secs = segments
         .last()
         .map(|s| (s.end_ms / 1000) as i64)