- Created startup configuration system for automatic relay and account setup
- New StartupConfig struct with optional relay and nsec fields
- Load/save functions for startup_config.json
- Config file location: ~/.local/share/notedeck/settings/startup_config.json
- Integrated startup config into app initialization
- Automatically adds account from nsec if provided
- Automatically connects to relay if provided
- Loads before default relay configuration
- Removed all deck creation functionality from side panel
- Removed NewDeck, SwitchDeck, and EditDeck actions
- Removed deck UI elements (add button, deck list)
- Simplified side panel to show only essential controls
- Cleaned up unused code (DECK_ICON_SIZE, unused imports)
- Added documentation
- STARTUP_CONFIG.md with detailed usage instructions
- startup_config.json.example with configuration template
This allows users to configure their preferred relay and identity once in a
config file rather than having to set it up each time the application starts.
