- Introduce `MCPServer` to support connecting to MCP servers via stdio, SSE, or HTTP.
- Implement tool fetching, management, and invocation through MCP.
- Add `WithMCPServer` method to `ToolBox` for seamless tool integration.
- Extend schema package to handle raw JSON schemas for MCP tools.
- Update documentation with MCP usage guidelines and examples.
- Migrate `compress_image.go` to `internal/imageutil` for better encapsulation.
- Reorganize LLM provider implementations into distinct packages (`google`, `openai`, and `anthropic`).
- Replace `go_llm` package name with `llm`.
- Refactor internal APIs for improved clarity, including renaming `anthropic` to `anthropicImpl` and `google` to `googleImpl`.
- Add helper methods and restructure message handling for better separation of concerns.