Drives /projects/:name/mcp over the real Streamable HTTP transport with a
fake websearch upstream: tools/list must serve `websearch_fetch_content`
(every name matching the OpenAI function-name charset), calling that wire
name must reach the upstream as bare `fetch_content`, and a legacy client
echoing the canonical `websearch/fetch_content` must still route.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JaFvfHrQyUKCGv6o3N2Wir
