V191 - V176 CHARACTERS + PER-ACCOUNT ACTIVATE FLAG + HIDDEN PASSWORD - NO BACKUPS

Base: V176 character import/export behavior.

Session change only:
- Each account has its own independent flag under [Drakhysys Account Activate].
- Example keys: DRAKHYSYS Activate, KRONAS Activate.
- Login checks only the requested account's flag.
- Successful login sets only that account flag to 1.
- Logout sets only the logged-in account flag to 0.
- Delete clears only the deleted account flag before the existing V176 deletion flow.
- Legacy V190 per-account-section Activate values are ignored, so stale V190 values do not block V191.

Preserved from V176:
- Native Character File import behavior.
- Native account-scoped Export behavior.
- Character folder/router behavior.
- No automatic character backups/restoration.

UI retained from V190:
- New-account naming restriction.
- Password can be typed while visually hidden.
