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

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

whisper_local/hotkey.py

@@ -0,0 +1,57 @@
+"""Hotkey-Listener via evdev für Push-to-Talk."""
+
+import asyncio
+import logging
+from pathlib import Path
+from typing import Callable, Coroutine
+
+import evdev
+from evdev import InputDevice, categorize, ecodes
+
+logger = logging.getLogger(__name__)
+
+AsyncCallback = Callable[[], Coroutine]
+
+
+def find_keyboard_device() -> InputDevice:
+    """Findet das erste Keyboard-Device in /dev/input/."""
+    devices = [InputDevice(path) for path in evdev.list_devices()]
+    for device in devices:
+        capabilities = device.capabilities(verbose=True)
+        for (etype_name, _etype_code), events in capabilities.items():
+            if etype_name == "EV_KEY":
+                key_names = [name for name, _code in events]
+                if "KEY_A" in key_names:
+                    logger.info("Keyboard gefunden: %s (%s)", device.name, device.path)
+                    return device
+    raise RuntimeError("Kein Keyboard-Device gefunden in /dev/input/")
+
+
+class HotkeyListener:
+    def __init__(self, key_name: str = "KEY_F12"):
+        self.key_name = key_name
+        self.key_code = ecodes.ecodes.get(key_name)
+        if self.key_code is None:
+            raise ValueError(f"Unbekannter Key-Name: {key_name}")
+        self.on_press: AsyncCallback | None = None
+        self.on_release: AsyncCallback | None = None
+
+    async def _handle_key_event(self, key_down: bool) -> None:
+        """Ruft den passenden Callback auf."""
+        if key_down and self.on_press:
+            await self.on_press()
+        elif not key_down and self.on_release:
+            await self.on_release()
+
+    async def listen(self) -> None:
+        """Lauscht auf evdev-Events der konfigurierten Taste."""
+        device = find_keyboard_device()
+        logger.info("Lausche auf %s auf %s", self.key_name, device.name)
+        async for event in device.async_read_loop():
+            if event.type == ecodes.EV_KEY and event.code == self.key_code:
+                if event.value == 1:  # Key down
+                    logger.debug("%s gedrückt", self.key_name)
+                    await self._handle_key_event(key_down=True)
+                elif event.value == 0:  # Key up
+                    logger.debug("%s losgelassen", self.key_name)
+                    await self._handle_key_event(key_down=False)