Fix xcodebuild/Xcode GUI build for SwiftBridging header missing

[Kyle-Ye]

Summary

• Fix SwiftBridging header not found when building with xcodebuild or Xcode GUI
• Replace -isystem include path approach with symlinks from target include directories (OpenAttributeGraphCxx, Utilities) to the SwiftBridging module
• Move SwiftBridging.h out of nested include/SwiftBridging/ subdirectory to the module root

Test plan

• Build with swift build via command line
• Build with xcodebuild to verify header resolution
• Open in Xcode GUI and verify the project builds without errors

[augmentcode]

🤖 Augment PR Summary

Summary: Fixes Xcode/xcodebuild builds failing to find the Swift bridging header by avoiding a global -isystem path.
Changes: Moves SwiftBridging.h to the module root and exposes it via include-dir symlinks from OpenAttributeGraphCxx and Utilities.

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[augmentcode]

Review completed. 2 suggestions posted.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 10.12%. Comparing base (d6910f8) to head (09ac624).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@## main #206 +/- ##
=======================================
Coverage 10.12% 10.12% =======================================
Files 28 28 Lines 820 820 =======================================
Hits 83 83 Misses 737 737 

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