V113 - Moonlight + local BG2 accounts

- The Moonlight player uses the account controls inside the streamed BG2 interface.
- The account itself is created locally on the PC running BG2, not on the Moonlight client PC.
- The Moonlight client needs no account files and no helper installation.
- The old custom Windows URL-protocol transport is no longer used.
- BG2 writes an encrypted local request mailbox; a local helper on the BG2 PC processes it.
- CREATE ACCOUNT is enabled only for an account name that does not yet exist.
- LOG IN is enabled only after that account has actually been created.
- Each account owns its own folder containing account.json, account.log, and that account's .CHR files.
- account.log records account creation, successful login/logout, character load, and character save. Passwords are never logged.
- LOAD ACCOUNT CHARACTER reads only the currently logged-in account folder.
- SAVE ACCOUNT CHARACTER writes only to the currently logged-in account folder.
- No character backup, restoration, synchronization, copying, or respawn behavior is added.
