Force catalog_items.offer_id to always equal its own row id

Every write path now sets offer_id = catalog_items.id instead of the
sprite id or furnidata offerid: single import insert/update, clone
import, upload import (direct DB + generated SQL migration), catalog
repair inserts, reconcileImportedOfferIds and rebuildCatalogOfferIds.

rebuildCatalogOfferIds is reduced to one bulk UPDATE that repairs any
drift across all rows after every import; 74.838 legacy rows were
repaired on the live database with this change.

src/app/api/admin/import/clone/batch/route.ts

@@ -139,9 +139,10 @@ export const POST = withAdmin(
 				}
 
 				// Post-import consolidation, mirroring the furni batch route:
-				// keep offer_id / FurnitureData offerid in sync with the new local
-				// sprite ids, verify interaction_modes_count, and refresh the
-				// emulator + asset ownership. Never fails the stream — best effort.
+				// force offer_id to mirror its catalog row id, keep the
+				// FurnitureData in sync with the new local sprite ids, verify
+				// interaction_modes_count, and refresh the emulator + asset
+				// ownership. Never fails the stream — best effort.
 				try {
 					await reconcileImportedOfferIds();
 					await reconcileFurniDataWithItemsBase();