feat: add pynput hotkey backend for Windows

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

whisper_local/hotkey/_pynput.py

@@ -0,0 +1,78 @@
+"""Hotkey-Listener via pynput für Push-to-Talk (Windows / Fallback)."""
+
+import asyncio
+import logging
+import re
+
+from pynput.keyboard import Key, Listener
+
+from whisper_local.hotkey import AsyncCallback
+
+logger = logging.getLogger(__name__)
+
+
+def _evdev_to_pynput_key(evdev_name: str) -> Key:
+    """Übersetzt evdev Key-Namen (z.B. KEY_F12) ins pynput-Format."""
+    match = re.match(r"^KEY_(F\d+)$", evdev_name)
+    if match:
+        attr = match.group(1).lower()
+        key = getattr(Key, attr, None)
+        if key is not None:
+            return key
+
+    # Versuche direkte Zuordnung (KEY_SPACE -> space, etc.)
+    suffix = evdev_name.removeprefix("KEY_").lower()
+    key = getattr(Key, suffix, None)
+    if key is not None:
+        return key
+
+    raise ValueError(f"Unbekannter Key-Name: {evdev_name}")
+
+
+class PynputHotkeyListener:
+    def __init__(self, key_name: str = "KEY_F12"):
+        self.key_name = key_name
+        self._target_key = _evdev_to_pynput_key(key_name)
+        self.on_press: AsyncCallback | None = None
+        self.on_release: AsyncCallback | None = None
+        self._loop: asyncio.AbstractEventLoop | 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()
+
+    def _schedule_callback(self, key_down: bool) -> None:
+        """Bridged den Thread-Callback zu asyncio."""
+        if self._loop is None:
+            return
+        self._loop.call_soon_threadsafe(
+            asyncio.ensure_future,
+            self._handle_key_event(key_down),
+        )
+
+    def _on_press(self, key) -> None:
+        if key == self._target_key:
+            logger.debug("%s gedrückt", self.key_name)
+            self._schedule_callback(key_down=True)
+
+    def _on_release(self, key) -> None:
+        if key == self._target_key:
+            logger.debug("%s losgelassen", self.key_name)
+            self._schedule_callback(key_down=False)
+
+    async def listen(self) -> None:
+        """Startet den pynput Keyboard-Listener und blockiert async."""
+        self._loop = asyncio.get_running_loop()
+        stop_event = asyncio.Event()
+
+        listener = Listener(on_press=self._on_press, on_release=self._on_release)
+        listener.start()
+        logger.info("Lausche auf %s via pynput", self.key_name)
+
+        try:
+            await stop_event.wait()  # Blockiert bis zum Programmende
+        finally:
+            listener.stop()