feat: add hotkey module with evdev push-to-talk listener

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

tests/test_hotkey.py

@@ -0,0 +1,38 @@
+import asyncio
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from whisper_local.hotkey import HotkeyListener
+
+
+@pytest.fixture
+def listener():
+    return HotkeyListener(key_name="KEY_F12")
+
+
+class TestHotkeyListener:
+    def test_init_stores_key_name(self, listener):
+        assert listener.key_name == "KEY_F12"
+
+    @pytest.mark.asyncio
+    async def test_key_down_calls_callback(self, listener):
+        on_press = AsyncMock()
+        listener.on_press = on_press
+
+        await listener._handle_key_event(key_down=True)
+        on_press.assert_awaited_once()
+
+    @pytest.mark.asyncio
+    async def test_key_up_calls_callback(self, listener):
+        on_release = AsyncMock()
+        listener.on_release = on_release
+
+        await listener._handle_key_event(key_down=False)
+        on_release.assert_awaited_once()
+
+    @pytest.mark.asyncio
+    async def test_no_callback_no_error(self, listener):
+        # Kein Callback gesetzt — soll nicht crashen
+        await listener._handle_key_event(key_down=True)
+        await listener._handle_key_event(key_down=False)