V256 - LEAVE EXPORT DISABLED + PLAYER 1 ARBITRATION + NO STANDARD AUTO-SAVE
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Player leave
------------
- A real remote player 2-6 leaving creates exactly one leave event.
- The departed account is marked non-exportable immediately for the current runtime.
- Export is blocked before the player's account/slot binding is cleared.
- If that same account legitimately rejoins, normal Export access is restored.
- Character files are not copied, restored, backed up, or respawned by this rule.

Arbitration
-----------
- Only BG2's genuine multiplayer host AND local multiplayer Player 1 may force Arbitration.
- If Player 1 is on the world screen when a remote player leaves, Arbitration opens immediately.
- If another modal/screen temporarily prevents the transition, the same one-shot event stays queued and opens Arbitration when the world becomes available.
- Clients cannot force Arbitration, including clients temporarily reporting player ID 1 during connection.
- Pressing Play consumes the leave event; it does not continuously reopen Arbitration.

Join protection
---------------
- V254's one-shot Join protection is retained.
- An already-connected player cannot issue another Direct-IP/session Join request from gameplay.

Auto-Save
---------
- The installer disables the standard Auto-Save and Auto-Save-TOB entries in override/SAVENAME.2DA.
- If SAVENAME.2DA is already customized, all other rows are preserved.
- If it does not exist, V256 installs SAVENAME_NO_AUTOSAVE.2DA as the starting table.
- No .bak or automatic backup copy is created by this operation.

Import / Export
---------------
- Native account-bound Import behavior remains available.
- Normal Export remains available for active/connected accounts.
- A departed account stays Export-disabled until a legitimate rejoin restores access.

Testing
-------
- RUN_IN_GAME_ACCOUNT_TESTS.bat runs the V256 suite.
- Tests cover Player 1 host authority, players 2-6 leave events, client rejection,
  deferred one-shot Arbitration, departed-account Export lock/rejoin restoration,
  Join one-shot behavior, native Import/Export regressions, and SAVENAME.2DA handling.
