V166 - PLAYER-BOUND MANUAL EXPORT / ACCOUNT FLAGS / ONE EXPORT FILE

1. Import remains exactly account-isolated through the active account's characters mirror.
2. Import Saved Game remains disabled; Import Character goes directly to Character File.
3. Export Character is manual again from the Character/Record screen.
4. Export is available only when the selected character is bound to the logged-in account.
5. The export filename is locked to the character's stable id (dra_1, dra_2, kro_1, ...).
6. Re-exporting the same character overwrites that same stable file; it cannot create a second manual export filename.
7. The characters junction still points only to characters_<active account>, so Export cannot write into another account folder.
8. Logout deactivates the account flag and disconnects its mirror; login reactivates only that account.
9. Periodic/background character export is disabled. Export is user-triggered.
10. No automatic character backups, history copies, or deleted-character respawn are created.
