Reads AppsUseLightTheme from HKCU\...\Personalize and applies
Colors::dark() or Colors::light() via cx.set_global() so the UI
matches the system theme.

- Mic capture via cpal (WASAPI) with multi-channel downmix
- Opus encoding (mono/VoIP, 20ms frames) wrapped in Ogg-Opus container
- Two-window GPUI UI: main control window + frameless waveform popup
- Recording toggle via UI button (hotkey removed)
- System tray icon with icon
- Opens explorer.exe on recording save
- Debug logging across the full pipeline (capture/encode/finish)