Google Secret Manager provider backed by the real GCP APIs.

The implementation talks to Secret Manager and Cloud KMS over HTTPS using a bearer token supplied via environment variables. Secret payloads store the full SecretRecord structure serialized as JSON so we can faithfully restore metadata when reading secrets back.

greentic-secrets-provider-gcp-sm

Google Secret Manager backend for the Greentic secrets core, wiring GCP secret operations into the unified secrets interface.