Update availability macros for OS 26 and 27

[Kyle-Ye]

Summary

• update OpenSwiftUI_v7_0 to use the unified OS 26 platform versions
• add OpenSwiftUI_v8_0 for OS 27 across SwiftPM and Xcode configurations
• refresh the SwiftPM lockfile origin hash

Testing

• swift package resolve
• swift package dump-package
• git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 25.92%. Comparing base (29cb8a3) to head (75a9d89).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #933      +/-   ##
==========================================
+ Coverage   25.91%   25.92%   +0.01%     
==========================================
  Files         721      721              
  Lines       50788    50788              
==========================================
+ Hits        13162    13168       +6     
+ Misses      37626    37620       -6     

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[augmentcode]

🤖 Augment PR Summary

Summary: Updates the custom AvailabilityMacro mappings to use the unified OS 26 platform versions and introduces OpenSwiftUI_v8_0 for OS 27.
Changes: Applies the new mappings consistently in both Xcode .xcconfig files and SwiftPM Package.swift, and refreshes the SwiftPM lockfile origin hash.

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[augmentcode]

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