fix(ook): address Copilot review — stale process, XSS presets, localStorage

- Detect crashed rtl_433 process via poll() and clean up stale state
  instead of permanently blocking restarts with 409
- Replace innerHTML+onclick preset rendering with createElement/addEventListener
  to prevent XSS via crafted localStorage frequency values
- Normalize preset frequencies to toFixed(3) on save and render
- Add try/catch + shape validation to loadPresets() for corrupted localStorage

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

routes/ook.py

@@ -63,7 +63,11 @@ def start_ook() -> Response:
 
     with app_module.ook_lock:
         if app_module.ook_process:
-            return jsonify({'status': 'error', 'message': 'OOK decoder already running'}), 409
+            # If the process exited/crashed, clean up stale state and allow restart
+            if app_module.ook_process.poll() is not None:
+                cleanup_ook(emit_status=False)
+            else:
+                return jsonify({'status': 'error', 'message': 'OOK decoder already running'}), 409
 
         data = request.json or {}