fix(fc2a): align CI with FabledRulebook — lint + short unit tests only

The CI failure resolving 'postgres' hostname was the symptom; the cause is
that the workflow violated FabledRulebook/forgejo.md's "CI philosophy —
lint + short unit tests only" rule. Integration tests against a real
Postgres are supposed to run locally via docker-compose, not in CI.

Changes:
- Marked 8 DB-dependent test files with @pytest.mark.integration:
  test_tag_service, test_importer, test_gallery_service, test_api_gallery,
  test_api_tags, test_api_settings, test_api_import_admin, test_maintenance.
- CI workflow drops the postgres/redis service containers and the alembic
  upgrade smoke step entirely.
- Pytest invocation in CI changes to `pytest -v -m "not integration"`.
- Added pytest marker registration to pyproject.toml.
- DB_PASSWORD and SECRET_KEY env vars retained because config.py reads
  them at import time even though unit tests don't actually use them
  (set to placeholder values).

What CI now runs:
- ruff check
- pytest on the 6 unit test files: test_slug, test_paths,
  test_migration_0002, test_thumbnailer, test_celery_smoke,
  test_tasks_register.
- npm install + npm run build

What CI no longer runs:
- alembic upgrade (no live DB)
- the 8 integration test files (these run locally via docker-compose)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_api_gallery.py

@@ -5,6 +5,8 @@ import pytest
 from backend.app import create_app
 from backend.app.models import ImageRecord
 
+pytestmark = pytest.mark.integration
+
 
 @pytest.fixture
 async def app():

tests/test_api_import_admin.py

@@ -6,6 +6,8 @@ from backend.app import create_app
 from backend.app.celery_app import celery
 from backend.app.models import ImportBatch, ImportTask
 
+pytestmark = pytest.mark.integration
+
 
 @pytest.fixture(autouse=True)
 def eager():

tests/test_api_settings.py

@@ -2,6 +2,8 @@ import pytest
 
 from backend.app import create_app
 
+pytestmark = pytest.mark.integration
+
 
 @pytest.fixture
 async def app():

tests/test_api_tags.py

@@ -2,6 +2,8 @@ import pytest
 
 from backend.app import create_app
 
+pytestmark = pytest.mark.integration
+
 
 @pytest.fixture
 async def app():

tests/test_gallery_service.py

@@ -10,6 +10,8 @@ from backend.app.services.gallery_service import (
     encode_cursor,
 )
 
+pytestmark = pytest.mark.integration
+
 
 def _now():
     return datetime.now(UTC)

tests/test_importer.py

@@ -11,6 +11,8 @@ import pytest
 from PIL import Image
 from sqlalchemy import select
 
+pytestmark = pytest.mark.integration
+
 from backend.app.models import Artist, ImageRecord, ImportSettings, Tag, TagKind
 from backend.app.services.importer import Importer, SkipReason
 from backend.app.services.thumbnailer import Thumbnailer

tests/test_maintenance.py

@@ -9,6 +9,8 @@ import pytest
 from backend.app.celery_app import celery
 from backend.app.models import ImportBatch, ImportTask
 
+pytestmark = pytest.mark.integration
+
 
 @pytest.fixture(autouse=True)
 def eager():

tests/test_tag_service.py

@@ -3,6 +3,8 @@ import pytest
 from backend.app.models import TagKind
 from backend.app.services.tag_service import TagService, TagValidationError
 
+pytestmark = pytest.mark.integration
+
 
 @pytest.mark.asyncio
 async def test_find_or_create_creates(db):