fix: suppress key-repeat events in pynput hotkey listener

Holding the hotkey caused dozens of on_press callbacks due to OS key-repeat.
Added a _pressed guard flag so only the first press and actual release fire.

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

tests/test_hotkey.py

@@ -89,3 +89,26 @@ class TestPynputHotkeyListener:
         listener = PynputHotkeyListener("KEY_F12")
         await listener._handle_key_event(key_down=True)
         await listener._handle_key_event(key_down=False)
+
+    def test_key_repeat_ignored(self):
+        from whisper_local.hotkey._pynput import PynputHotkeyListener
+        from pynput.keyboard import Key
+        listener = PynputHotkeyListener("KEY_F12")
+        listener._loop = MagicMock()
+
+        # Erstes Press — wird durchgelassen
+        listener._on_press(Key.f12)
+        assert listener._loop.call_soon_threadsafe.call_count == 1
+
+        # Wiederholte Presses (Key-Repeat) — werden ignoriert
+        listener._on_press(Key.f12)
+        listener._on_press(Key.f12)
+        assert listener._loop.call_soon_threadsafe.call_count == 1
+
+        # Release — wird durchgelassen
+        listener._on_release(Key.f12)
+        assert listener._loop.call_soon_threadsafe.call_count == 2
+
+        # Erneutes Release ohne Press — wird ignoriert
+        listener._on_release(Key.f12)
+        assert listener._loop.call_soon_threadsafe.call_count == 2