Add TPEN-side sender workflow for shared OpenAPI artifact sync to cubap/rerum_openapi

[Copilot]

This PR adds TPEN-services as the canonical editing surface for the shared OpenAPI artifact and automates export into cubap/rerum_openapi via PR updates. It establishes a standard provider path in this repo while keeping consumers anchored to the receiver repo artifact.

• Canonical provider artifact (TPEN-owned)

  • Added openapi/components/tpen-services-shared-components.openapi.yaml as the source-of-truth shared contract artifact in a discoverable OpenAPI components layout.

• Sender sync workflow (cross-repo PR automation)

  • Added .github/workflows/sync_tpen_shared_openapi.yaml.
  • Triggers on:
    • pushes to development that touch the shared artifact (or the workflow itself)
    • manual workflow_dispatch
  • Behavior:
    • checks out cubap/rerum_openapi
    • copies TPEN provider artifact to schemas/openapi/tpen-services-shared-components.openapi.yaml
    • opens or updates a dedicated sync PR branch in the receiver repo

• Repo-level guardrail for required sync files

  • Extended existing existence checks to assert both:
    • openapi/components/tpen-services-shared-components.openapi.yaml
    • .github/workflows/sync_tpen_shared_openapi.yaml

# .github/workflows/sync_tpen_shared_openapi.yaml
- name: Copy shared OpenAPI artifact into receiver repository
  run: |
    mkdir -p rerum_openapi/schemas/openapi
    cp openapi/components/tpen-services-shared-components.openapi.yaml \
      rerum_openapi/schemas/openapi/tpen-services-shared-components.openapi.yaml