fix: handle SIGINT so Ctrl+C cleanly exits the app

Qt's event loop swallows SIGINT. Add a periodic timer to let Python
process signals and route SIGINT to the clean quit handler.

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

src/my_memory/app.py

@@ -2,9 +2,10 @@
 
 from __future__ import annotations
 
+import signal
 import sys
 
-from PySide6.QtCore import QByteArray
+from PySide6.QtCore import QByteArray, QTimer
 from PySide6.QtGui import QAction, QIcon
 from PySide6.QtNetwork import QLocalServer, QLocalSocket
 from PySide6.QtWidgets import QApplication, QMenu, QSystemTrayIcon
@@ -141,4 +142,13 @@ class MyMemoryApp:
     def run(self) -> int:
         """Run the application event loop."""
         self.setup_tray()
+
+        # Let Python's SIGINT handler fire inside the Qt event loop.
+        # A zero-interval timer gives Python a chance to run signal handlers
+        # between Qt event loop iterations.
+        timer = QTimer()
+        timer.start(500)
+        timer.timeout.connect(lambda: None)
+        signal.signal(signal.SIGINT, lambda *_: self._quit())
+
         return self._app.exec()