Switch to Homebrew Luau for building LuaFileSystem

[mentatbot]

This PR modifies the approach to use Homebrew-installed Luau instead of the internal headers. Key changes:

1. Modified GitHub workflow to install Luau via Homebrew and configure paths correctly
2. Simplified lfs.c to use standard includes without compatibility layer
3. Updated CMake configuration to find and use Homebrew Luau

This approach should solve previous compilation issues while making the code simpler and more maintainable.

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[mentatbot]

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[mentatbot]

I've updated the PR with fixes for the build failure. The main changes:

1. Fixed the include statements in lfs.c:

   • Changed from <luau.h> to standard Lua headers: <lua.h>, <lauxlib.h>, <lualib.h>
   • It appears Homebrew Luau uses standard Lua naming conventions for its headers

2. Added better library detection in the GitHub workflow:

   • Now inspects the actual Homebrew Luau installation structure
   • Uses find to locate the actual library file (*.dylib or *.a)
   • Provides detailed diagnostic output to help troubleshoot

3. Enhanced the CMake FindLua.cmake module:

   • Tries multiple library names (luau, lua, liblua, libluau)
   • Uses GLOB to find any .dylib or .a file in the lib directory
   • Provides multiple fallbacks for different potential library paths

These changes should fix the 'file not found' error and make the build process more robust by handling variations in how Homebrew might install Luau.

[mentatbot]

You are out of Mentat credits; I won't iterate on CI failure. You can view and refresh your credits here.

[mentatbot]

I've changed the approach to solve the build issues. After analyzing the failures, it seems the Homebrew Luau headers might not be properly detected or installed in the standard include paths.

New approach:

1. Use internal headers, Homebrew library - Use the Luau headers from the project's source tree (source/cpp/luau/) while still using the Homebrew Luau library for linking
2. Multiple include paths - Added several include paths to the compiler flags to ensure all headers can be found
3. Added compatibility definition - Added LUA_COMPAT_5_1=1 to maintain compatibility with Lua 5.1 APIs

This hybrid approach gives us the best of both worlds:

• We know the headers will be found since they're directly in the repo
• We still benefit from the Homebrew Luau library installation
• We don't need the complex compatibility layer from the original implementation

This should be more robust and reliable for the build process while achieving the original goal of moving away from a complex custom compatibility layer.