v1.1.0 — MCP server

Added

• MCP server: knock --mcp serves the Model Context Protocol over stdio
  with knock_enumerate, knock_ct_lookup and knock_registrable_domain
  tools (structured output, progress notifications, cancellation). Hand-rolled
  JSON-RPC, so still zero runtime dependencies.
• llms.txt, an agent-oriented API reference shipped in the package, and
  AGENTS.md / CLAUDE.md contributor guidance for coding agents.