FEATURE: Settings GUI window

[BenGWeeks]

Create a proper graphical settings window to replace JSON file editing.

Description

Implement a user-friendly settings GUI instead of requiring users to edit config.json manually.

UI Requirements

• Clean, simple interface matching Nod.ie's design
• Organized into logical sections
• Real-time preview of changes
• Save/Cancel buttons
• Reset to defaults option

Settings Categories

Audio

• Microphone device selection
• Speaker device selection
• Audio levels
• Noise suppression options

Voice Assistant

• Voice model selection
• Language preferences
• Response style settings
• Wake word configuration

Integrations

• n8n webhook URL
• LND connection settings
• MCP server configuration

Interface

• Hotkey customization
• Window position
• Visual themes
• Notification preferences

Advanced

• Unmute backend URL
• Debug logging level
• Performance tuning

From TODO.md items #6 and #10