Add ORBSymbolAnimator and ORBAnimation support

[Kyle-Ye]

Add ORBAnimation, ORBSymbolAnimator, and ORBSymbolAnimatorObserver with full API surface.

Changes

ObjC Headers (OpenRenderBoxCxx/include/OpenRenderBoxObjC/Animation/)

• ORBAnimation.h — @interface ORBAnimation : NSObject <NSCopying> with animation composition API
• ORBSymbolAnimatorObserver.h — @protocol ORBSymbolAnimatorObserver <NSObject>
• ORBSymbolAnimator.h — @interface ORBSymbolAnimator : NSObject with full property/method surface

ObjC Implementations (OpenRenderBoxCxx/Animation/)

• ORBAnimation.m / ORBSymbolAnimator.m — stub @implementation guarded with #if ORB_OBJC_FOUNDATION

Swift Shims (OpenRenderBox/Animation/)

• ORBAnimation.swift — NSObject subclass with full API matching ObjC interface (#if !canImport(ObjectiveC))
• ORBSymbolAnimator.swift — NSObject subclass + ORBSymbolAnimatorObserver protocol (#if !canImport(ObjectiveC))

Exports

• OpenRenderBoxShims/Export.swift — added ORBAnimation, ORBSymbolAnimator, ORBSymbolAnimatorObserver type aliases

Tests

• AnimationTests.swift — 8 test cases covering all animation composition methods
• SymbolAnimatorTests.swift — 5 test cases covering properties, animation management, and geometry

Dependencies

• Updated Package.resolved for DarwinPrivateFrameworks (Add RBAnimation and RBSymbolAnimator headers DarwinPrivateFrameworks#33)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 74 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (ba06b06) to head (6c7fee1).

Files with missing lines	Patch %	Lines
...es/OpenRenderBox/Animation/ORBSymbolAnimator.swift	0.00%	53 Missing ⚠️
Sources/OpenRenderBox/Animation/ORBAnimation.swift	0.00%	21 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main     #23   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files          4       6    +2     
  Lines        123     197   +74     
=====================================
- Misses       123     197   +74     

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