V235 - PURGE STALE ACCOUNTS WITHOUT CHARACTER FOLDER - NO BACKUPS

Rule:
- characters_<accountname> is the authority for whether an account still exists.
- If Baldur.lua still contains an account/password/session record but the matching
  characters_<accountname> directory is gone, setup permanently clears that
  account verifier and its Activate/Disabled flags.
- The local router repeats the same cleanup once when it starts.
- If a stale verifier somehow reaches LOGIN, a missing account character folder
  causes that verifier to be erased immediately instead of reappearing as an
  account without a folder.
- Existing accounts whose matching characters_<accountname> directory exists are
  left untouched.
- No character folder, account, backup, restore copy, or replacement is created.
