Add visionOS support

[Kyle-Ye]

Summary

• Add visionOS platform support to OpenSwiftUI

Test Plan

• All tests pass in both SwiftUI and OpenSwiftUI environments
• Verified TimelineSchedule implementations match SwiftUI behavior
• Floating-point comparisons use isApproximatelyEqual for reliability

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 24.58%. Comparing base (0af53c9) to head (590bcbb).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...utton/ButtonStyle/TODO/BorderlessButtonStyle.swift	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #499      +/-   ##
==========================================
+ Coverage   24.56%   24.58%   +0.01%     
==========================================
  Files         477      476       -1     
  Lines       27677    27672       -5     
==========================================
+ Hits         6798     6802       +4     
+ Misses      20879    20870       -9     

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