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`

app_urls/fetcher/tests/test_config.py

@@ -0,0 +1,68 @@
+import json
+import os
+
+from django.conf import settings
+from django.test import SimpleTestCase
+
+SCHEDULED_TASKS_PATH = os.path.join(
+    os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))),
+    "scheduled_tasks.json",
+)
+
+
+class ScheduledTasksFixtureTests(SimpleTestCase):
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        with open(SCHEDULED_TASKS_PATH) as f:
+            cls.data = json.load(f)
+        cls.periodic_tasks = [
+            e
+            for e in cls.data
+            if e.get("model") == "django_celery_beat.periodictask"
+        ]
+
+    def test_json_is_valid_and_loads(self):
+        self.assertIsInstance(self.data, list)
+        self.assertTrue(len(self.data) > 0)
+
+    def test_periodic_task_primary_keys_are_unique(self):
+        pks = [e["pk"] for e in self.periodic_tasks]
+        self.assertEqual(len(pks), len(set(pks)))
+
+    def test_notify_status_has_unique_pk(self):
+        notify = [
+            e
+            for e in self.periodic_tasks
+            if e["fields"].get("task") == "fetcher.tasks.notify_status"
+        ]
+        self.assertEqual(len(notify), 1)
+        other_pks = {
+            e["pk"]
+            for e in self.periodic_tasks
+            if e["fields"].get("task") != "fetcher.tasks.notify_status"
+        }
+        self.assertNotIn(notify[0]["pk"], other_pks)
+
+    def test_interval_schedule_primary_keys_are_unique(self):
+        schedules = [e for e in self.data if e["model"] == "django_celery_beat.intervalschedule"]
+        pks = [e["pk"] for e in schedules]
+        self.assertEqual(len(pks), len(set(pks)))
+
+    def test_expected_critical_tasks_present(self):
+        tasks = {e["fields"].get("task") for e in self.periodic_tasks}
+        self.assertIn("fetcher.tasks.process_raw_urls", tasks)
+        self.assertIn("fetcher.tasks.fetch_feeds", tasks)
+        self.assertIn("fetcher.tasks.notify_status", tasks)
+
+
+class CeleryQueueSettingsTests(SimpleTestCase):
+    def test_contains_worker_queues(self):
+        queues = [q.name for q in settings.CELERY_TASK_QUEUES]
+        self.assertIn("default", queues)
+        self.assertIn("light", queues)
+        self.assertIn("heavy", queues)
+
+    def test_does_not_contain_deprecated_low_queue(self):
+        queues = [q.name for q in settings.CELERY_TASK_QUEUES]
+        self.assertNotIn("low", queues)