Update deployment documentation to reflect that the MCPSigningKey is
persisted in Mnemosyne's database and used directly for minting team
JWTs, rather than being shared with Daedalus via vault. Remove the
obsolete vault variable reference and document the key rotation
procedure.
- Change app healthcheck from /live/ to /ready/ to verify full
readiness including dependencies (DB, Neo4j, S3)
- Increase healthcheck timeout from 5s to 10s to accommodate
dependency checks
- Add S3 bucket connectivity check to readiness probe
- Update deployment documentation to use /srv/mnemosyne instead
of /opt/mnemosyne as the compose project directory
