ECDSA P-256 / SHA-256 detached signature over /.well-known/mcp/manifest.json
(raw DER at manifest.json.sig). The `npx datamancy` adapter pins the public key
and verifies this on every fetch.

Signature (DER, base64):

MEUCIHsc/2OMURTrsM4dkH7cNCASwuS4PxpGxhe92hUFF2+jAiEA+vrSix6ktt/IM0+v8y6N2sA/Antt0qpzEmkrTWNp1Co=