fix: correct test imports and health endpoint assertions

- Fix import in test_db_utils.py: use app.models instead of backend.app.models
- Update health endpoint test to expect 'ok' status and infrastructure keys
- Add CHANGELOG entries for PyPI proxy performance improvements

backend/tests/unit/test_db_utils.py

@@ -8,7 +8,7 @@ class TestArtifactRepository:
 
     def test_batch_dependency_values_formatting(self):
         """batch_upsert_dependencies should format values correctly."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         deps = [
             ("_pypi", "numpy", ">=1.21.0"),
@@ -29,7 +29,7 @@ class TestArtifactRepository:
 
     def test_empty_dependencies_returns_empty_list(self):
         """Empty dependency list should return empty values."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         values = ArtifactRepository._format_dependency_values("abc123", [])
 
@@ -37,7 +37,7 @@ class TestArtifactRepository:
 
     def test_format_dependency_values_preserves_special_characters(self):
         """Version constraints with special characters should be preserved."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         deps = [
             ("_pypi", "package-name", ">=1.0.0,<2.0.0"),
@@ -51,7 +51,7 @@ class TestArtifactRepository:
 
     def test_batch_upsert_dependencies_returns_zero_for_empty(self):
         """batch_upsert_dependencies should return 0 for empty list without DB call."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         mock_db = MagicMock()
         repo = ArtifactRepository(mock_db)
@@ -64,8 +64,8 @@ class TestArtifactRepository:
 
     def test_get_or_create_artifact_builds_correct_statement(self):
         """get_or_create_artifact should use ON CONFLICT DO UPDATE."""
-        from backend.app.db_utils import ArtifactRepository
-        from backend.app.models import Artifact
+        from app.db_utils import ArtifactRepository
+        from app.models import Artifact
 
         mock_db = MagicMock()
         mock_result = MagicMock()
@@ -88,7 +88,7 @@ class TestArtifactRepository:
 
     def test_get_or_create_artifact_existing_not_created(self):
         """get_or_create_artifact should return created=False for existing artifact."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         mock_db = MagicMock()
         mock_result = MagicMock()
@@ -108,7 +108,7 @@ class TestArtifactRepository:
 
     def test_get_cached_url_with_artifact_returns_tuple(self):
         """get_cached_url_with_artifact should return (CachedUrl, Artifact) tuple."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         mock_db = MagicMock()
         mock_cached_url = MagicMock()
@@ -125,7 +125,7 @@ class TestArtifactRepository:
 
     def test_get_cached_url_with_artifact_returns_none_when_not_found(self):
         """get_cached_url_with_artifact should return None when URL not cached."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         mock_db = MagicMock()
         mock_db.query.return_value.join.return_value.filter.return_value.first.return_value = None
@@ -137,7 +137,7 @@ class TestArtifactRepository:
 
     def test_get_artifact_dependencies_returns_list(self):
         """get_artifact_dependencies should return list of dependencies."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         mock_db = MagicMock()
         mock_dep1 = MagicMock()
@@ -156,7 +156,7 @@ class TestArtifactRepository:
 
     def test_get_artifact_dependencies_returns_empty_list(self):
         """get_artifact_dependencies should return empty list when no dependencies."""
-        from backend.app.db_utils import ArtifactRepository
+        from app.db_utils import ArtifactRepository
 
         mock_db = MagicMock()
         mock_db.query.return_value.filter.return_value.all.return_value = []