V254 - HOST-ONLY ARBITRATION; PLAYERS 2-6 STAY IN GAME; ONE-SHOT JOIN

INSTALL
1. Close every BG2 window so the previous Lua runtime is unloaded.
2. Extract this package and run SETUP_IN_GAME_ACCOUNTS.bat.
3. Choose the BG2 game folder and Documents/profile folder, then restart BG2.

CHANGES
- Host authority now uses BG2 e:IsHosting(), not multiplayerLocalPlayerID alone.
  A joining client that temporarily reports player ID 1 is still treated as a client.
- Only the actual host may queue/open Arbitration for a real remote join or leave.
  Players 2-6 do not open Arbitration on their own game client.
- OnPlayerSelection character-slot assignment is allowed only while the actual
  host is actively on the Arbitration screen. World/gameplay background pulses
  no longer send character-assignment controls.
- Slot ownership changes are one-shot while awaiting the engine response, so
  redraws cannot repeatedly resend the same OnPlayerSelection request.
- Direct-IP JoinGameIPAddress and native session-list Join requests are wrapped
  in a one-shot guard. Once BG2 is already in a multiplayer session, stale
  button/Enter events cannot submit another Join request and trigger a misleading
  server occupied/full/busy popup.
- V253 Play transition protection remains: pressing Play consumes the current
  Arbitration event before native Done and does not reopen the same event.
- Normal account-bound Import/Export remains unchanged. The shared characters
  folder stays denied and only characters_<logged account> is accessible.
- No automatic character backups, restore copies, numbered copies, or respawn
  behavior were added.

VALIDATION
- Executed Lua tests cover real-host vs client authority, including a client with
  temporary player ID 1.
- Tests verify host slot assignment does not run during world gameplay and that
  repeated redraws send at most one pending assignment.
- Tests verify Direct-IP and session-list Join calls are one-shot and blocked
  after multiplayer connection.
- 37 account/multiplayer execution tests plus 6 focused native Import/Export
  regression checks pass in the development environment.
- Run RUN_IN_GAME_ACCOUNT_TESTS.bat for the packaged V254 checks.

LIVE TEST
1. Host creates/loads the game.
2. Player 2 joins and completes character creation.
3. Host sees Arbitration only for the actual join event, then presses Play.
4. Player 2 must remain in gameplay without an Arbitration popup.
5. Repeat for players 3-6. They must not receive a second Join/server occupied
   popup after already entering the game.
6. Disconnect one remote player: the host may receive one Arbitration visit for
   that real leave event; remaining clients stay in gameplay.
