The topic grids (PM system + wizard) showed extra categories like «سیم»,
«کابل», «ثبثب», «dsfg». Those rows were leftover junk in material_categories
from earlier testing — previously invisible because the frontend hardcoded
the 8-topic list; the API-driven topic grid surfaced them. The rows are
deleted (they had no references) and the seeder now deletes any category
outside the 8 canonical slugs, so a re-seed always yields exactly the same
8 categories as before. Dump refreshed from the clean state.