fix(launcher): improve game path auto detection

[lshw54]

What

Game path auto-detection could fail when the INI registry path pointed at HKEY_LOCAL_MACHINE, because the launcher stripped the HKLM prefix and only read HKCU. Users then had to manually choose the game executable even when the install path was available from registry or a standard install location.

Fix

Teach detect_game_path to build registry lookup candidates from the INI hive prefix.

Explicit HKEY_LOCAL_MACHINE paths now read HKLM first, with HKCU as a compatibility fallback. Explicit HKEY_CURRENT_USER paths read HKCU, while unprefixed paths keep the historical HKCU-first behavior and then try HKLM.

If registry detection still returns empty, fall back to common Program Files install paths using the INI executable template to derive the game exe name. Successful registry or default-path detections are written back to Config.xml for future launches.

Updates frontend callers to pass the INI exe template, regenerates bindings, and adds regression coverage for HKLM-prefixed registry detection plus default install-path candidate generation.

Closes #284