New usage-limit bucket "cinder_cove" tied to a product called "Cowork"

The usage-limits schema, parsed by the new teo zod schema, adds a cinder_cove field alongside the existing five_hour/seven_day buckets. When present in the parsed response, the settings UI renders it as a separate usage bar titled "Claude Code and Cowork credit," described as a one-time credit with an optional expiry drawn from resets_at. The bar stays hidden until the backend actually sends cinder_cove.