V174 - MIRRORED ACCOUNT FOLDER EXPORT LIST / RENAME / OVERWRITE / NO BACKUPS

- Import behavior is unchanged.
- Login mounts characters -> characters_<account>.
- Export list is built from the real .CHR filenames in that currently mirrored account folder.
- Export no longer depends on BG2's cached cross-account list or binding metadata to display rows.
- Selecting an existing row fills the normal Export filename box for overwrite.
- The filename box remains editable, so another valid filename can be saved inside the same active account folder.
- Account switching replaces the folder snapshot with the newly active account only.
- Logout disconnects/deactivates the account mirror.
- No automatic character backups or deleted-character restoration.
