feat: add GUI authentication and fix build configuration
Major improvements to build system, authentication flow, and user experience:
Build System:
- Configure common source set for shared security/network code
- Fix compilation errors by properly organizing source sets
- Add Mod Menu integration for configuration GUI
Client-Side Authentication:
- Replace Slingshot with official Bluesky identity resolution APIs
- Use com.atproto.identity.resolveHandle for standard handle resolution
- Improve error handling and user feedback
- Add /atproto config and /atproto gui commands
New Features:
- Add AtProtoConfigScreen for GUI-based authentication
- Integrate with Mod Menu for easy access to settings
- No-typing-required login flow with visual feedback
- Client-side password handling with security notices
Code Organization:
- Move security classes to src/common/kotlin/com/jollywhoppers/security/
- Move network classes to src/common/kotlin/com/jollywhoppers/network/
- Organize server code under atproto/server/ package
- Organize client code under atproto/client/ package
- Move example code to docs/examples/
This update resolves all compilation errors and provides a much better
user experience with GUI-based authentication.