Everruns servers publish an MCP server card and auth.md

An Everruns server now describes itself to agents. /.well-known/mcp/server-card.json is an MCP Server Card (SEP-1649), and /auth.md explains both credential paths: OAuth for the MCP endpoint and personal access tokens for the REST API. Both are generated from the running server’s configuration, so a self-hosted deployment describes itself correctly. Under AUTH_MODE=none they say no credentials are required.

The descriptions of create_agent, create_session and create_message also state their argument constraints, so an agent gets them right on the first call.

See Authentication. #3533, #3530