Add CI/CD GitHub Actions workflow for dev image builds

- Run tests on push/PR to main
- Build and push Docker image to GHCR as :dev and :dev-<sha> on push to main
- Document image pull/run instructions in README

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

README.md

@@ -19,4 +19,32 @@ docker compose up --build
 
 Then open `http://localhost:3001` and create an account. PostgreSQL data is kept
 in the `postgres-data` Docker volume, so it survives app and container restarts.
-To remove the database as well, run `docker compose down -v`.
+To remove the database as well, run `docker compose down -v`.
+
+## CI/CD
+
+On every push to `main`, GitHub Actions (`.github/workflows/ci-cd.yml`) runs the
+test suite, then builds and publishes a dev image to the GitHub Container
+Registry:
+
+```
+ghcr.io/odweta/fakturovac:dev
+```
+
+A commit-pinned tag (`ghcr.io/odweta/fakturovac:dev-<short-sha>`) is published
+alongside `:dev` for traceability. Pull requests only run the test job.
+
+To pull and run the latest dev image in a testing environment:
+
+```bash
+docker login ghcr.io -u <your-github-username>   # only needed if the package is private
+docker pull ghcr.io/odweta/fakturovac:dev
+docker run -d -p 3001:3001 \
+  -e DATABASE_URL=postgres://fakturovac:fakturovac@<db-host>:5432/fakturovac \
+  -e NODE_ENV=production \
+  ghcr.io/odweta/fakturovac:dev
+```
+
+The package's visibility (public/private) is managed under the repository's
+**Packages** settings on GitHub; no extra secrets are required since the
+workflow authenticates with the built-in `GITHUB_TOKEN`.