V292 - V291 native Export and legacy registered account folder fix

1. Native Export DONE explicitly authorizes the chosen 1-8 character filename
   through both the original BG2 export INI channel and the established account
   route channel. The router accepts only a matching active account and filename.
2. Fresh unconfirmed root .CHR/.BIO files have a 120-second processing grace,
   rather than being deleted after 2 seconds while BG2 may still be flushing its
   Export request. No foreign file is automatically moved into an account folder.
3. Existing registered accounts, such as an older Kronas account, can create
   their own missing characters/Kronas folder on PASSWORD-VALIDATED login.
   The exact registration must already be present in Baldur.lua. No new account
   password or registration is generated, and no old character files move.
4. Keep V291's account-only Export list and BG2 native Import/Export panels,
   plus per-account settings, campaigns, and unassigned-root cleanup.

Close ALL BG2/InfinityLoader instances before running setup. Select the
correct Documents profile containing Baldur.lua. Test with a new uniquely named
character and verify its .CHR appears in characters/<logged account>.
Do not manually delete files while BG2 is running. Account files are never
backed up, copied, or deleted during this migration. Live Windows test needed.
