Use sql\`count(*)::int\` instead of selecting appointments.id, which was
causing TS2339 under noUncheckedIndexedAccess (arr[0] is T | undefined).
Import sql from @groombook/db. Use countRow?.count ?? 0 to stay
noUncheckedIndexedAccess-safe.
Matches the working implementation in apps/api/src/routes/pets.ts:365.
Co-Authored-By: Paperclip <noreply@paperclip.ing>