Delete one kept inspection, its feedback and its file

Gone from the database at once (the database overwrites deleted pages). Leftover bytes in the database's files on disk are cleared by the daily sweep at the latest, and database backups age out within 60 days. A kept file goes too, and is unreadable at once: its encryption key is deleted with the record and the encrypted file is removed from disk. The exception is the hosting provider's whole-disk images (7 kept, one a day), which hold the encrypted file and the server key until they rotate out.