Self-management MCP: administer the gateway through its own protocol

[selic]

Expose gateway administration as an MCP server (a built-in "admin" toolset), so the gateway can be managed conversationally through any MCP client instead of config edits + redeploys.

Tool / toolset control

• Enable/disable individual tools and whole toolsets at runtime.
• List current state: which servers, toolsets, and tools are active, and for whom.

Server management

• Add/remove/update upstream MCP servers (endpoint, transport, auth) without redeploying the gateway.

User management

• Manage users/principals and their access: which toolsets/tools each user or client can see and call.

Notes

• Admin toolset must itself be permission-gated (only admin principals see it).
• Changes should persist (not just in-memory) and survive restarts.