docs: strip stale TODO/verify verbiage from gamedata + MERGE_READINESS

- gamedata WriteFieldList_FieldPathSite comment: drop the 'fills the Windows
  midhook TODO' / 'VERIFY ON HARDWARE' / docs/FORCE_RESEND ref; keep the RE fact.
- MERGE_READINESS: remove the REMAINING/TODO(windows) section (cited removed
  scaffolding SetFieldPathRegister/SetSpoof/SetCallback/SetOneShot).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>