[Initiative] API-Driven Bare Repository Provisioning

[juliuskrah]

Summary

Implement API-driven bare repository provisioning so GitStore can create and initialise repositories without using a manual init script. Repository creation should be exposed through service APIs and default to bare repositories suitable for remote Git transport.

Scope

In Scope

• Add a repository-create API flow that provisions a bare repository in gitstore-git-service.
• Ensure the API path supports idempotency (create-if-not-exists semantics where appropriate).
• Initialize required refs/default branch metadata for a newly created bare repo.
• Return clear errors for invalid names, permission issues, and already-existing repositories.
• Add integration tests covering successful create, duplicate create, and invalid input cases.
• Document API-first bare repository bootstrap flow and deprecate manual script-first guidance.

Out of Scope

• Namespace model changes (tracked in [Initiative] Namespaces #39).
• Full repository management UI.
• SSH key management and access policy changes.

Acceptance Criteria

• A client can create a bare repository through API calls without running the init script.
• New repositories are created in bare mode and are immediately usable by Git transport operations.
• Duplicate creation requests are handled deterministically (clear error or idempotent success).
• Integration tests validate repository create and bootstrap behaviour end-to-end.
• Documentation includes API examples for bare repository creation.

Dependencies

• Subtask of: [Initiative] API driven repository creation #67
• Blocked by: [Initiative] Decouple API from Git Storage via gRPC Git Service #65

Tracking

• Milestone: TBD