Add unit tests and Gitea CI workflow for bug fixes

- Add fetcher/tests/ with 21 tests covering all bug fixes:
  - test_utils: get_with_protocol URL normalization (5 tests)
  - test_config: scheduled_tasks.json PK uniqueness, Celery queue
    settings (7 tests)
  - test_publish: URL routing and view for /task/publish_<id>/ (4 tests)
  - test_template_field: url_detail.html renders images_url field (2 tests)
  - test_search_postprocess: URL host filtering and param stripping (3 tests)
- Replace empty fetcher/tests.py with tests/ package
- Add .gitea/workflows/test.yml: runs on PRs and pushes to main,
  installs dependencies and runs `manage.py test fetcher.tests`

.gitea/workflows/test.yml

@@ -0,0 +1,57 @@
+name: Tests
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    services:
+      postgres:
+        image: postgres:17
+        env:
+          POSTGRES_DB: matitos
+          POSTGRES_USER: supermatitos
+          POSTGRES_PASSWORD: supermatitos
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd pg_isready
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+
+    env:
+      DJANGO_SECRET_KEY: ci-test-secret
+      DJANGO_ALLOWED_HOSTS: '*'
+      DJANGO_ALLOWED_ORIGINS: 'http://localhost'
+      DB_NAME: matitos
+      DB_USER: supermatitos
+      DB_PASSWORD: supermatitos
+      DB_HOST: localhost
+      DB_PORT: '5432'
+      REDIS_CACHE_HOST: localhost
+      REDIS_CACHE_PORT: '6379'
+      REDIS_CELERY_HOST: localhost
+      REDIS_CELERY_PORT: '6379'
+      PATH_LOGS_DIRECTORY: /tmp/logs
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+          cache: 'pip'
+          cache-dependency-path: app_urls/requirements.txt
+
+      - name: Install dependencies
+        run: pip install -r app_urls/requirements.txt
+
+      - name: Run tests
+        working-directory: app_urls
+        run: python manage.py test fetcher.tests -v 2