Update permissions for Linux

[TheDechev]

Summary

This PR improves the Linux user experience by ensuring executable files in the runtime/ directory have proper execute permissions when the repository is cloned. This eliminates the need for Linux users to manually run chmod +x after cloning and prevents executable permission changes from appearing as unstaged modifications in Git, providing a cleaner development workflow.

Changes Made

1. Updated .gitattributes

• Added explicit binary marking for runtime executables to ensure Git properly handles file permissions
• Targets runtime/*.exe, runtime/Update.exe, and runtime/Path*of*Building-PoE2.exe

2. Set executable permissions in Git repository

• Used chmod +x to set executable permissions on local filesystem
• Used git update-index --chmod=+x to make Git track the files as executable in repository metadata
• This combination ensures new clones will have the correct permissions automatically
• Updates permissions for the current release's executable files (Path of Building-PoE2.exe and Update.exe)
  • Permission changes (mode 100644→100755) are included in commit 13beaa9fc

3. Updated CONTRIBUTING.md

• Added a brief note for Linux users about executable permissions being automatically handled

Technical Details

The improvement addresses:

• Git only tracks the owner execute bit, not full permissions
• Binary files without proper Git attributes can lose executable status during clone operations
• Linux systems require explicit execute permissions to run binary files

The solution:

• Uses Git's built-in permission tracking via git update-index --chmod=+x
• Leverages .gitattributes to ensure consistent handling across platforms
• Works for both Windows (no impact) and Linux (improves user experience)

Verification

• ✅ Windows: No impact, executables work as before
• ✅ Linux: Fresh clones will have proper executable permissions
• ✅ Existing clones: Permissions will be corrected on next git pull
• ✅ Git metadata: Executable permissions are now tracked in repository (confirmed via git ls-files --stage)

Backward Compatibility

• No breaking changes
• Windows users are unaffected
• Existing Linux users who have already fixed permissions locally are unaffected
• Only benefits new Linux users who clone the repository

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Improves: Linux user experience by eliminating manual chmod +x requirement and preventing permission-related unstaged changes in Git
Platforms: Primarily benefits Linux users, no impact on Windows

[TheDechev]

@Wires77 , will you be able to take a look please?