feat: Add microphone selection to system tray menu

[somesingelse]

Hi! Thanks for the amazing app.

I found myself frequently needing to switch input devices, so I added a dynamic "Microphone" submenu to the system tray (placed right below the Model selection).

Changes included:

• Added a tray menu builder for available microphones in tray.rs.
• Reused the existing commands::audio::get_available_microphones and set_selected_microphone to handle the logic.
• Added mic_select:* event handling in lib.rs to seamlessly switch the active microphone and refresh the tray UI.
• Added the "Microphone" translation key to both English and Russian locales.

Tested locally and works perfectly. Let me know if any adjustments are needed!