Fix CI integration test failures

- Add proxy-body-size annotation to allow unlimited uploads via nginx
- Add requires_direct_s3 marker for tests needing direct MinIO access
- Exclude requires_direct_s3 tests from CI (can't access MinIO from outside K8s)
- Add auto-migration for tag ref_count triggers to ensure they exist

backend/app/database.py

@@ -170,6 +170,62 @@ def _run_migrations():
             END IF;
         END $$;
         """,
+        # Create ref_count trigger functions for tags (ensures triggers exist even if initial migration wasn't run)
+        """
+        CREATE OR REPLACE FUNCTION increment_artifact_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE artifacts SET ref_count = ref_count + 1 WHERE id = NEW.artifact_id;
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        """
+        CREATE OR REPLACE FUNCTION decrement_artifact_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE artifacts SET ref_count = ref_count - 1 WHERE id = OLD.artifact_id;
+            RETURN OLD;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        """
+        CREATE OR REPLACE FUNCTION update_artifact_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            IF OLD.artifact_id != NEW.artifact_id THEN
+                UPDATE artifacts SET ref_count = ref_count - 1 WHERE id = OLD.artifact_id;
+                UPDATE artifacts SET ref_count = ref_count + 1 WHERE id = NEW.artifact_id;
+            END IF;
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        # Create triggers for tags ref_count management
+        """
+        DO $$
+        BEGIN
+            -- Drop and recreate triggers to ensure they're current
+            DROP TRIGGER IF EXISTS tags_ref_count_insert_trigger ON tags;
+            CREATE TRIGGER tags_ref_count_insert_trigger
+                AFTER INSERT ON tags
+                FOR EACH ROW
+                EXECUTE FUNCTION increment_artifact_ref_count();
+
+            DROP TRIGGER IF EXISTS tags_ref_count_delete_trigger ON tags;
+            CREATE TRIGGER tags_ref_count_delete_trigger
+                AFTER DELETE ON tags
+                FOR EACH ROW
+                EXECUTE FUNCTION decrement_artifact_ref_count();
+
+            DROP TRIGGER IF EXISTS tags_ref_count_update_trigger ON tags;
+            CREATE TRIGGER tags_ref_count_update_trigger
+                AFTER UPDATE ON tags
+                FOR EACH ROW
+                WHEN (OLD.artifact_id IS DISTINCT FROM NEW.artifact_id)
+                EXECUTE FUNCTION update_artifact_ref_count();
+        END $$;
+        """,
         # Create ref_count trigger functions for package_versions
         """
         CREATE OR REPLACE FUNCTION increment_version_ref_count()