Added image generation support and various improvements.
- Added image generation support
- Added support for stablediffusion.cpp, including model library and installation/compilation options
- Added support for Pollinations, OpenAI and OpenRouter image generation providers
- Added image editing support
- Redesigned chat interface
- Added support for STDIO MCP servers in the Flatpak version
- Improved lazy tool loading by automatically exposing tool schemas when needed
- Improved MCP server error handling
- Various bug fixes and stability improvements
