Isolate CI/deploy tests from production DATABASE_URL (#24)

## Summary
- Root cause: `docker-compose.yml` used `${DATABASE_URL:-…}`, so the Act runner’s host/`prod` `DATABASE_URL` was interpolated into the web service. Containerized deploy tests then ran against shared Postgres instead of the bundled compose `db`.
- Stop reading host `DATABASE_URL` in compose (use `COMPOSE_DATABASE_URL` override only).
- Deploy docker step: unset DB secrets, dedicated compose project name, `up --wait db`, force test `DATABASE_URL` to `postgres://scha:scha@db:5432/scha`, `down -v` on exit (ephemeral DB).
- Clear `DATABASE_URL`/`DB_HOST` in `unittests.yml` / `ci.yml` so host sqlite-fallback tests cannot hit prod either.

## Test plan
- [ ] Merge to `master` and watch Unit Tests + Deploy docker job.
- [ ] Confirm docker step connects only to compose `db` (no traffic/errors against `10.0.0.230`).
- [ ] Confirm `docker compose -p scha-ci-<sha> …` volumes cleaned after job (`down -v`).
- [ ] Local: `docker compose up --build` still works with bundled Postgres.

Reviewed-on: #24

.gitea/workflows/ci.yml

@@ -23,5 +23,8 @@ jobs:
         env:
           DJANGO_ENV: dev
           DJANGO_SECRET_KEY: test-secret-key
+          # Explicitly clear DB vars so host/prod DATABASE_URL cannot leak in.
+          DATABASE_URL: ""
+          DB_HOST: ""
         run: |
           uv run python manage.py test

.gitea/workflows/deploy.yml

@@ -20,15 +20,27 @@ jobs:
       - name: Build Docker image
         run: docker compose build
 
+      # Ephemeral local Postgres only — never inherit host DATABASE_URL (prod).
       - name: Run containerized tests
         run: |
-          docker compose up -d db
-          docker compose run --rm --entrypoint "" \
+          set -euo pipefail
+          # Drop host/prod DB secrets so compose cannot interpolate them.
+          unset DATABASE_URL DB_HOST DB_NAME DB_USER DB_PASSWORD DB_PORT \
+            COMPOSE_DATABASE_URL DJANGO_ENV DJANGO_SECRET_KEY DJANGO_DEBUG \
+            DJANGO_ALLOWED_HOSTS || true
+
+          PROJECT="scha-ci-${{ gitea.event.workflow_run.head_sha }}"
+          cleanup() { docker compose -p "$PROJECT" down -v --remove-orphans || true; }
+          trap cleanup EXIT
+
+          docker compose -p "$PROJECT" up -d --wait db
+          docker compose -p "$PROJECT" run --rm --no-deps --entrypoint "" \
             -e DJANGO_ENV=dev \
             -e DJANGO_SECRET_KEY=test-secret-key \
+            -e DJANGO_DEBUG=true \
+            -e DJANGO_ALLOWED_HOSTS=localhost,127.0.0.1,testserver \
             -e DATABASE_URL=postgres://scha:scha@db:5432/scha \
             web uv run python manage.py test
-          docker compose down
 
   deploy:
     if: gitea.event.workflow_run.conclusion == 'success' && gitea.event.workflow_run.event == 'push'

.gitea/workflows/unittests.yml

@@ -25,5 +25,8 @@ jobs:
         env:
           DJANGO_ENV: dev
           DJANGO_SECRET_KEY: test-secret-key
+          # Explicitly clear DB vars so host/prod DATABASE_URL cannot leak in.
+          DATABASE_URL: ""
+          DB_HOST: ""
         run: |
           uv run python manage.py test