Restructure the container setup to support registry-based deployment:
the default docker-compose.yml now pulls a prebuilt app image from the
Gitea container registry instead of building locally, while a new
docker-compose.dev.yml override preserves the local build + integration
test workflow for development.
Why:
- Production and self-hosting should consume a published image, not
rebuild from source on the host. The default `docker compose up` now
pulls the app image (git.linuxhg.com/bookhoard/bookhoard) alongside the
public postgres image, with no build step required.
- Development still needs to build from source and run integration
tests, so those concerns move to an override file the Makefile applies.
Shared config (env, volumes, ports, healthchecks) lives in one place to
avoid drift between environments.
Changes:
- docker-compose.yml (prod base): the app service now references
`image: git.linuxhg.com/bookhoard/bookhoard:${IMAGE_TAG:-latest}` instead
of a build context. The tests service is removed (moved to the
override). IMAGE_TAG lets deployers pin or roll back a specific version.
- docker-compose.dev.yml (new override): adds the local `build:` context
for the app and defines the integration `tests` service (profile-gated).
Everything else is inherited from the base file via compose merging.
- Makefile: introduce a COMPOSE variable that merges the base and
override (`-f docker-compose.yml -f docker-compose.dev.yml`); all dev
targets now use it. Plain `docker compose` against the base file only
remains the production path.
- README: quickstart updated to pull and start prebuilt images; clone URL
points at the Gitea instance.
The development workflow (`make rebuild-app`, `make test-integration`,
etc.) is functionally unchanged.
