- vector_sync route: rename the response dict from `body` to `resp` so it no
longer shadows the request `body` (maintenance trap)
- scanner: comment the intentional files-vs-text purge timing asymmetry
- tests: add the all-text-types-disabled backstop case (empty allow-set)
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>