Save confirmed business setup progress

Read/resume owner-led bookkeeping for the business selected by x-organization-id. Requires manage:banking, bank_transactions:read for GET and bank_transactions:read_write for PUT. Updates obey normal subscription permissions. Stored progress is assistant-reported, not evidence of a bank connection, posted accounting or an active external routine. No secrets. This endpoint does not create jobs or change books. Send the complete state and expectedRevision from GET (zero for first save). Stale edits return 409; reload and merge. An identical retry of the immediately preceding write returns reused=true. Active routines require provider ID, approved scope, schedule, timezone and approval/verification timestamps; opening balances marked confirmed require evidence. Mapped bank register IDs must belong to this business.