refactor: update and improve MCP server

[sinedied]

This pull request removes support for the legacy SSE transport protocol from the Burger MCP server, streamlining the codebase and documentation to focus exclusively on the Streamable HTTP transport. It also updates the MCP tool registration API and bumps the marked dependency version in the agent web app.

Transport protocol simplification:

• Removed all SSE transport support from the server code (packages/burger-mcp/src/server.ts), including endpoints, session handling, and shutdown logic. Only Streamable HTTP transport is now supported. [1] [2] [3] [4]
• Updated documentation to remove references to SSE transport and clarify that only Streamable HTTP is supported (README.md, docs/blog/01-release/release.md, packages/burger-mcp/README.md). [1] [2] [3] [4] [5]

API improvements:

• Refactored MCP tool registration to use server.registerTool instead of server.tool, providing a more explicit and flexible API (packages/burger-mcp/src/mcp.ts). [1] [2] [3]

Dependency updates:

• Upgraded the marked package in the agent web app to version 17.x (packages/agent-webapp/package.json).