This pull request removes all support for IBM Secrets Manager as a source for the application's master encryption secret. The code now exclusively retrieves the master secret from the OPENRAG_ENCRYPTION_KEY environment variable. All related IBM SDK dependencies and tests have been removed.

Key changes:

Dependency cleanup:

• Removed ibm-secrets-manager-sdk from the pyproject.toml dependencies, as it is no longer needed.

Encryption secret retrieval changes:

• Simplified the get_master_secret function in src/utils/encryption.py to only retrieve the secret from the OPENRAG_ENCRYPTION_KEY environment variable, eliminating all logic and error handling related to IBM Secrets Manager.

Test cleanup:

• Deleted the entire tests/unit/test_ibm_encryption.py file, removing all tests that covered IBM Secrets Manager integration and related fallback logic.