fix: eager-load server defaults on StorageObjects to avoid MissingGreenlet

publish_version -> create_server_object_payload -> storage_payload reads
item.created_at on a sync helper. Without eager_defaults, server-default
columns stay unloaded after INSERT, the next sync read triggers a lazy
refresh through the async driver, and MissingGreenlet fires.

Enable mapper-level eager_defaults on StorageObjects so server-default
columns (created_at, updated_at, ...) are round-tripped into the ORM
object immediately after INSERT. No other table or session config
touched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

common/src/common/db/models/storage.py

@@ -10,6 +10,13 @@ from common.db.base import Base
 
 class StorageObjects(Base):
     __tablename__ = "storage_objects"
+    # Force SQLAlchemy to round-trip server-default columns (created_at,
+    # updated_at, ...) via a follow-up SELECT after INSERT. Without this,
+    # attributes populated by `server_default` stay unloaded on the ORM
+    # object and the next sync read (e.g. storage_payload in storage_api.py)
+    # triggers a lazy refresh through the async driver, which raises
+    # MissingGreenlet because the read happens outside an awaitable.
+    __mapper_args__ = {"eager_defaults": "auto"}
     __table_args__ = (
         Index("fk_storage_created_by", "created_by"),
         Index("idx_storage_content_hash", "content_hash"),