[Kyle-Ye]

Add content transition descriptors and effect types to the C/Objective-C API, native implementation, Swift fallback, and RenderBox shims. Support effect timing, animation indices, raw arguments, and transition value copying. Native copies share C++ storage and detach on mutation.

Store and copy spring animation descriptors, and update the DarwinPrivateFrameworks pin to the merged transition APIs. Focused validation passed nine native tests and six system RenderBox compatibility tests with remote dependencies.

Dependency

• DarwinPrivateFrameworks #84: add transition descriptor APIs (merged).

Related to OpenSwiftUIProject/OpenSwiftUI#1206.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.77612% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 25.38%. Comparing base (f9a3964) to head (a171436).

Files with missing lines	Patch %	Lines
...ources/OpenRenderBox/Animation/ORBTransition.swift	95.72%	5 Missing ⚠️
Sources/OpenRenderBox/Animation/ORBAnimation.swift	88.23%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            main      #38       +/-   ##
==========================================
+ Coverage   0.50%   25.38%   +24.87%     
==========================================
  Files         13       14        +1     
  Lines        393      524      +131     
==========================================
+ Hits           2      133      +131     
  Misses       391      391               

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