[ ] GET /api/v1/repos/:owner/:name returns audience: { level, sentence }, computed for the caller.
[ ] The MCP tool that describes a repository returns the same field, with the same words.
[ ] Tests: the API and MCP give the same sentence for the same caller, and an anonymous caller gets the public sentence or a 404, never a private repository's names.
Part 4 of #809, after audienceOf lands.
Done looks like:
GET /api/v1/repos/:owner/:namereturnsaudience: { level, sentence }, computed for the caller.