V314: SETUP_IN_GAME_ACCOUNTS compatibility hotfix

- The old installer could report "V312 world pulse was not found uniquely".
- V314 finds the correct function and deduplicates only the two V312/V313
  pulse calls, preserving all account, character, and multiplayer functions.
- Running SETUP_IN_GAME_ACCOUNTS.bat again is supported; no separate installer.
- The host-leaves-party behavior from V313 is not otherwise changed.
- Account-session flags are not touched before the UI passes validation.
- No automatic character backups, deletes, or remount changes.

Close BaldurII.exe before running SETUP_IN_GAME_ACCOUNTS.bat.
Windows two-player behavior still needs live verification.
