Adds CommonLibF4 as a git submodule dependency and introduces a Windows `build.bat` helper. The script ensures `xmake` is installed, runs the plugin build, and reports success/failure with the expected staged output path, making local setup and builds more consistent.
Create a minimal Fallout 4 F4SE/CommonLibF4 starter repo with build, packaging, install, and rename scripts, plus initial plugin source, headers, and xmake configuration.
andrew