Add microphone picker and device management features

- Implement `list_input_devices` to retrieve and filter input-capable audio devices.
- Create `MicPickerDialog` for selecting and saving microphone settings.
- Add `set_env_value` function to update .env file with selected microphone index.
- Update UI components to integrate microphone selection functionality.
- Enhance tests for microphone device handling and environment variable management.

tests/test_mic.py

@@ -100,6 +100,32 @@ def test_returns_none_when_should_continue_stops_before_speech():
     assert result is None
 
 
+def test_list_input_devices_filters_to_input_capable(monkeypatch):
+    fake_devices = [
+        {"name": "Speakers", "max_input_channels": 0, "hostapi": 0},
+        {"name": "USB Mic", "max_input_channels": 2, "hostapi": 0},
+        {"name": "Line In", "max_input_channels": 1, "hostapi": 1},
+    ]
+    fake_hostapis = [{"name": "MME"}, {"name": "WASAPI"}]
+
+    class _FakeSoundDevice:
+        @staticmethod
+        def query_devices():
+            return fake_devices
+
+        @staticmethod
+        def query_hostapis(index):
+            return fake_hostapis[index]
+
+    monkeypatch.setitem(sys.modules, "sounddevice", _FakeSoundDevice())
+
+    devices = mic.list_input_devices()
+    assert devices == [
+        {"index": 1, "name": "USB Mic", "hostapi": "MME"},
+        {"index": 2, "name": "Line In", "hostapi": "WASAPI"},
+    ]
+
+
 def test_pcm_to_wav_bytes_round_trips_via_wave_module():
     import wave
     import io