[FEATURE]: Education AI Suite - Settings modal window to select microphone for Smart Classroom sample app

Description Extend the Settings modal to allow users to select their preferred audio input source for the Smart Classroom sample app. The modal should offer a dropdown or radio button group to choose between:

• Audio file upload (default)
• Enumerated microphone devices

The actual recording controls and real-time transcription will be handled elsewhere in the GUI.

Assumptions

• Audio input source selection is a configuration step, not an interaction point.
• Microphone enumeration is supported via browser APIs (e.g., navigator.mediaDevices.enumerateDevices()).
• The selected input source will be passed to the main window for interaction.

Dependencies

• Audio pipeline (ASR, diarization)
• GUI framework support enumerations of microphones

Expected Output

Settings modal with:

• Audio input source selector (file vs. mic)
• Dropdown listing available microphones (if mic is selected)
• Save/Apply button to persist selection

Acceptance Criteria

• Modal displays available audio input options
• Microphones are enumerated and selectable
• Selection is saved and reflected in main window behavior
• File upload remains default for October release