MCP RPC Surface (Entry)

This root file is now a short entry point.

Canonical MCP surface docs live in MDX:

• Built-in tools/resources (CLI command patterns): docs/start_here/cli_quick_recipes.mdx
• Dynamic tools/resources from Flutter app: docs/core/dynamic_tools_registry.mdx
• Connection targeting and retry model: docs/core/mcp_configuration.mdx
• CLI vs MCP usage guidance: docs/start_here/cli_vs_mcp.mdx

Why this changed

RPC surface details were moved into the docs site structure to keep documentation consistent for humans and AI agents.