PrintedItem (catalog: code, name, image, cached quantityonhand,
per-item threshold, bin) and PrintedItemTransaction (the ledger:
signed quantity change attributed to a badge-resolved employee).
Both registered in PLUGIN_TABLE_OWNERS; 0001 is a post-cutover real
baseline. The migration-guard test learns the new expected head.
Routes are a placeholder ping until the next stage - the scaffold's
list route imported the deleted scaffold model, which surfaces as an
empty 'Migration error' because the alembic env imports the models
package.