feat(server): add attachment ORM models and table provisioning

Adds 5 tables in the CargoTrace schema: attachment_category,
finished_goods_attachment, finished_goods_attachment_item,
finished_goods_attachment_location, finished_goods_box_attachment_item.
Includes a one-off create_all script and extends test cleanup.

Co-Authored-By: Claude <noreply@anthropic.com>

scripts/create_attachment_tables.py

@@ -0,0 +1,39 @@
+"""One-off: create the 5 attachment tables in the configured DB.
+
+Run from services/fastapi/ with the venv active:
+    python scripts/create_attachment_tables.py
+"""
+
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from app.core.database import Base, engine  # noqa: E402
+from app.models.attachment import (  # noqa: E402
+    AttachmentCategory,
+    FinishedGoodsAttachment,
+    FinishedGoodsAttachmentItem,
+    FinishedGoodsAttachmentLocation,
+    FinishedGoodsBoxAttachmentItem,
+)
+
+NEW_TABLES = [
+    AttachmentCategory,
+    FinishedGoodsAttachment,
+    FinishedGoodsAttachmentItem,
+    FinishedGoodsAttachmentLocation,
+    FinishedGoodsBoxAttachmentItem,
+]
+
+
+def main() -> None:
+    Base.metadata.create_all(
+        engine,
+        tables=[t.__table__ for t in NEW_TABLES],
+    )
+    print(f"Created {len(NEW_TABLES)} attachment tables.")
+
+
+if __name__ == "__main__":
+    main()