Api Account Reset

Reset the account: clear Platinur-generated state, optionally drop Platinur’s own warehouse namespaces, and UNBIND the warehouse engine so the account can choose a new one.

Owner/admin only and double-gated: the warehouse binding is otherwise fixed, so the JSON body must carry the typed confirmation {"confirm": "RESET", "drop_warehouse_objects": false}. drop_warehouse_objects opts into dropping ONLY Platinur’s env output + validation namespaces (never the customer’s raw/source schemas).