V168 - NATIVE EXPORT THROUGH THE ACTIVE ACCOUNT MIRROR

- Import behavior is unchanged: BG2 opens the native Character File importer and sees only the logged-in account folder through `characters`.
- Export now follows the same navigation model: the Record-screen Export button opens BG2's stock CHARACTER_EXPORT screen immediately.
- No custom account wait/export screen is shown before native Export.
- The active account flag/junction still decides the destination folder.
- The filename field is prefilled/locked to the selected character's one stable account id (dra_1, kro_1, etc.).
- BG2's stock Cancel, Done, and overwrite confirmation behavior are preserved.
- If an id is not yet cached, allocation happens asynchronously while the native Export screen remains open; the field becomes ready there.
- Logout deactivates the account flag and disconnects the account mirror.
- No automatic character backup, history copy, or deleted-character restoration is added.
