Accept the current Terms of Service for this business (admin)

Writes book_companies' marketing_attested_at/marketing_attested_by/marketing_attested_text (migration 0143). Deliberately its own route, not folded into PATCH /api/companies or PATCH /api/booking-policy: these three columns carry NO grant to `authenticated` at all, being a legal declaration about permission to contact other people, so a column grant would let any staff login mint or withdraw it via raw PostgREST (0143's own comment on that column group). Written with service-role, past this route's own admin gate, the same posture booking-policy.ts already uses for its own ungranted columns. `{ action: "attest" }` sets `marketing_attested_at` to now, `marketing_attested_by` to the caller's user id, and snapshots `MARKETING_ATTESTATION_TEXT` (consent.ts) into `marketing_attested_text` verbatim, so the string an admin agreed to and the string kept on file are the same value by construction. `{ action: "withdraw" }` clears `marketing_attested_at` back to null and leaves `marketing_attested_by`/`marketing_attested_text` alone as a record of the last declaration made: the audience rule (`canReceiveMarketing`, consent.ts) is time-scoped by `attested_at` alone, so this one flip instantly narrows the emailable audience back to explicit opt-ins for every customer at once, with nothing to backfill on the book_customers side. The widget-visibility toggle (`booking_marketing_optin_enabled`) is a SEPARATE column with its own grant to `authenticated`, and goes through the ordinary PATCH /api/companies save instead, since it is a display setting, not itself a consent record, so it does not belong on this route.