Integrate secret manager pattern for production secrets

[robertocarlous]

Body:

Relying exclusively on environment variables increases operational friction for secret rotation. Add documentation and an adapter layer to allow fetching secrets from a secrets manager (AWS Secrets Manager / Vault) while preserving env var fallback for local dev.

Acceptance Criteria:

• A secrets adapter module supports env fallback and a pluggable secret store.
• Documentation contains a recommended production secret storage workflow and rotation steps.
• No secret values are committed to the repo.

[susanyusuf]

Hi Maintainer, I am applying to implement a pluggable secrets adapter layer for the Backend repository to simplify production secret rotation and eliminate environment variable friction.
Pluggable Adapter Module: I will engineer a robust secrets management adapter supporting connection to an external secret store (such as AWS Secrets Manager or HashiCorp Vault) while gracefully falling back to local environment variables for development.

[dotunv]

I am interested in this issue