Fixes a Win64 multiplayer issue where player data (`players/*.dat`) could be mismatched because identity was effectively tied to connection-order `smallId` XUIDs.
Introduces a deterministic username-derived persistent XUID and integrates it into the existing XUID-based save pipeline.
- Added `Windows64_NameXuid` for deterministic `name -> persistent xuid` resolution
- On Win64 login (`PlayerList`), set `ServerPlayer::xuid` from username-based resolver
- Aligned local player `xuid` assignment (`Minecraft`) for create/init/respawn paths to use the same resolver
- Added Win64 local-self guard in `ClientConnection::handleAddPlayer` using name match to avoid duplicate local remote-player creation
- Kept `IQNet::GetPlayerByXuid` compatibility fallback behavior, while extending lookup to also resolve username-based XUIDs
- Moved implementation to `Minecraft.Client/Windows64/Windows64_NameXuid.h`; kept legacy `Win64NameXuid.h` as compatibility include
Rename migration is intentionally out of scope (same-name identity only).
- Skip QuadrantSignin (profile selector) on Windows64 in both LoadMenu
and CreateWorldMenu, proceeding directly to local play since Xbox Live
stubs always return true for IsSignedInLive()
- Fix IsLocalMultiplayerAvailable() to not require IsHiDef() on Windows64
- Allow pad-connected players to join without a profile sign-in check
- Fix ghost RemotePlayer creation by scanning all local player slots and
matching on server-assigned player index rather than controller slot,
fixing P3/P4 ghost entities when joining out of controller order
- Give each player a unique name (Player 1-4) based on controller index
instead of a single shared stub name
- Use raw XInput (XInputGetState) for secondary controller join detection,
bypassing the 4J toggle system which consumes all button presses before
game logic runs; uses a 120-frame latch for a reliable detection window
- Add .gitignore for Visual Studio build artifacts and output directories
