[Feature Request] MCP support

## Describe the solution you'd like

Add support for the Model Context Protocol (MCP) in both the backend agent tooling and the bot-creation UI so that end users can register and configure remote MCP servers without writing code. Specifically:

- On the “Create Bot” screen, provide a JSON-based configuration section where users can add on tool use configurations (Agent)

## Why the solution needed

- Emerging open standard: MCP has rapidly gained industry adoption—Anthropic open-sourced it, OpenAI and Google Gemini have added support, and many platforms (Block, Apollo, Replit, Sourcegraph, etc.) are integrating it ([blog post](https://thesof.medium.com/beyond-claude-using-openai-and-google-gemini-models-with-mcp-servers-eea3bc218ed0))

- Interoperability: Without built-in MCP support, developers must fork code or write custom integrations every time a new MCP server appears.

## Additional context

Some past discussions can be found: #816, #817