test(fence): owner filters in any form, statement writes under any name, core commits by list

The owner-filter check missed an aliased() model, an import alias, .in_() and
filter_by; four live inline filters on aliased VideoState go through owned_by now.
Cross-unit writes are seen under any import name, through sa.update and via
__table__. Core modules may commit only where CORE_COMMITS names the reason;
trim_read and audit.gc flush now and their callers commit. The pin target, the
debug-session header and a link's target fetch through owned_row. The docs
claim what the fence holds, and say what is beyond it.

backend/app/routes/notifications.py

@@ -78,8 +78,8 @@ def mark_read(
 ) -> dict:
     n = owned_or_404(db, Notification, notification_id, user, what="notification")
     n.read = True
-    db.commit()
     trim_read(db, user.id)
+    db.commit()
     return {"ok": True}
 
 
@@ -90,8 +90,8 @@ def mark_all_read(user: User = Depends(current_user), db: Session = Depends(get_
         .where(owned_by(Notification.user_id, user), Notification.read.is_(False))
         .values(read=True)
     )
-    db.commit()
     trim_read(db, user.id)
+    db.commit()
     return {"ok": True}