Make the nightly database-in-image refresh work on GitHub Actions #3182

Summary

The nightly database job refreshes a database-in-image project's image on CircleCI, but the GitHub Actions database job in .github/workflows/build-test-deploy.yml has never had any database-in-image handling. A GitHub Actions project with VORTEX_DB_IMAGE set gets no fresh image from its nightly run, and with the container_registry fetch source the Export DB step fails.

Details

How CircleCI does it

#3180 (for #3177) makes the CircleCI flow work. When VORTEX_DB_IMAGE and VORTEX_DB_IMAGE_BASE are set and VORTEX_FETCH_DB_SOURCE isn't container_registry, the Export DB step:

1. Runs vortex-fetch-db with the container_registry source and VORTEX_FETCH_DB_CONTAINER_REGISTRY_IMAGE_BASE passed in, so vortex-fetch-db-container-registry pulls the base image and tags it as VORTEX_DB_IMAGE. docker compose up then builds the database service from that clean base.
2. Runs vortex-provision with VORTEX_DB_IMAGE cleared, so the empty database is provisioned from the dump file. vortex-provision itself knows nothing about the base image.
3. Runs vortex-export-db with VORTEX_DB_IMAGE set, which exports the database as an image, and the Deploy DB image step pushes it with vortex-push-db-image.

What the GitHub Actions database job is missing

• The Adjust variables for a scheduled run step sets neither VORTEX_DB_IMAGE_BASE nor VORTEX_EXPORT_DB_CONTAINER_REGISTRY_PUSH_PROCEED.
• There's no Deploy DB image step. The push used to live inside vortex-export-db until Extract the container image deployment from 'export-db' into a dedicated script #2723 moved it into its own step, and only CircleCI got one.
• The Export DB step runs docker compose --progress quiet cp -L .data/db.sql cli:/app/.data/db.sql without || true, so it fails for the container_registry source, which fetches no dump file. CircleCI tolerates the missing file.
• It doesn't remove .data/db.sql after the import for database-in-image projects (CircleCI runs grep -q ^VORTEX_DB_IMAGE .env && rm .data/db.sql || true), so the cache stores both the dump and the image archive.
• It has none of the base image handling from the CircleCI Export DB step described above.
• The template's own database-in-image test workflows (DIDI-FI and DIDI-II in .circleci/vortex-test-common.yml) run on CircleCI only, so nothing exercises this path on GitHub Actions.

To fix

1. Set VORTEX_DB_IMAGE_BASE and VORTEX_EXPORT_DB_CONTAINER_REGISTRY_PUSH_PROCEED=1 for the scheduled run.
2. Add a Deploy DB image step that mirrors the CircleCI one.
3. Make Export DB tolerate a missing dump file, and remove the dump after the import for database-in-image projects.
4. Add the base image handling from the CircleCI Export DB step: tag the base through vortex-fetch-db with the container_registry source, and run vortex-provision with VORTEX_DB_IMAGE cleared.
5. Cover the flow in the template's GitHub Actions tests.