V241 - Law<gamefolderRouterSystem/> PERMANENT ACCOUNT CHARACTER ROUTING

The account folder router is now the authoritative character-folder system.
BG2's ordinary shared-character fallback is no longer restored by the router.

PERMANENT LAW / PRIORITY
1. plain characters = ACCESS DENIED
2. characters_<any other account> = ACCESS DENIED / NOT EXPOSED
3. characters_<logged account> = READABLE / IMPORTABLE / EXPORTABLE

IMPLEMENTATION
- Law constant: Law<gamefolderRouterSystem/>
- The law is checked before every account-router command.
- The law is also re-asserted continuously by the router pulse.
- When no valid account is active, the literal BG2 `characters` path is left denied/absent.
- Any unexpected real `characters` folder is moved out of the engine-visible name instead of accepted as a fallback.
- Historical shared files, when present, remain parked outside the live `characters` path.
- When a valid account is active, only readable_characters_<account> is created.
- BG2's literal `characters` engine path is then only a junction to that allowed account view.
- readable_characters_<account> points only to characters_<account>.
- Other readable account views are removed.
- Logout/router shutdown never restores the old shared `characters` directory.

PRESERVED FROM V240
- Direct-IP Join Game defaults to 127.0.0.1.
- Persistent account-bound multiplayer slot/character ownership.
- Departed player's live character is removed while ownership remains account-bound.
- Host is forced to Arbitration when a player leaves.
- No character backups or automatic restoration.
