activate_files

Provision the standard drive for an existing Files tab on this project, as opening the web tab does. Requires live editor membership and boards:read/write. Idempotent per canonical tab; returns the existing drive on retries. Does not change billing, quotas, release flags, storage credentials or upload bytes. Release admission, restore readiness and canonical-home checks remain enforced. Create a missing tab first with manage_sheets/add_sheet; Omit tabId to resolve the only active Files tab in the canonical room; multiple tabs require an explicit tabId (--sheet in CLI).