Phase 3: Speaker diarization and full transcription pipeline

- Implement DiarizeService with pyannote.audio speaker detection
- Build PipelineService combining transcribe → diarize → merge with
  overlap-based speaker assignment per segment
- Add pipeline.start and diarize.start IPC handlers
- Add run_pipeline Tauri command for full pipeline execution
- Wire frontend to use pipeline: speakers auto-created with colors,
  segments assigned to detected speakers
- Build SpeakerManager with rename support (double-click or edit button)
- Add speaker color coding throughout transcript display
- Add pyannote.audio dependency
- Tests: 24 Python (including merge logic), 6 Rust, 0 Svelte errors

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/commands/transcribe.rs

@@ -50,3 +50,55 @@ pub fn transcribe_file(
 
     Ok(response.payload)
 }
+
+/// Run the full transcription + diarization pipeline via the Python sidecar.
+#[tauri::command]
+pub fn run_pipeline(
+    file_path: String,
+    model: Option<String>,
+    device: Option<String>,
+    language: Option<String>,
+    num_speakers: Option<u32>,
+    min_speakers: Option<u32>,
+    max_speakers: Option<u32>,
+    skip_diarization: Option<bool>,
+) -> Result<Value, String> {
+    let python_path = std::env::current_dir()
+        .map_err(|e| e.to_string())?
+        .join("../python")
+        .canonicalize()
+        .map_err(|e| format!("Cannot find python directory: {e}"))?;
+
+    let python_path_str = python_path.to_string_lossy().to_string();
+
+    let manager = SidecarManager::new();
+    manager.start(&python_path_str)?;
+
+    let request_id = uuid::Uuid::new_v4().to_string();
+    let msg = IPCMessage::new(
+        &request_id,
+        "pipeline.start",
+        json!({
+            "file": file_path,
+            "model": model.unwrap_or_else(|| "base".to_string()),
+            "device": device.unwrap_or_else(|| "cpu".to_string()),
+            "compute_type": "int8",
+            "language": language,
+            "num_speakers": num_speakers,
+            "min_speakers": min_speakers,
+            "max_speakers": max_speakers,
+            "skip_diarization": skip_diarization.unwrap_or(false),
+        }),
+    );
+
+    let response = manager.send_and_receive(&msg)?;
+
+    if response.msg_type == "error" {
+        return Err(format!(
+            "Pipeline error: {}",
+            response.payload.get("message").and_then(|v| v.as_str()).unwrap_or("unknown")
+        ));
+    }
+
+    Ok(response.payload)
+}