Fix rotate effect merging for OpenSwiftUI renderer

[Kyle-Ye]

Close #878

Agent Summary

This updates display-list transform merging so 2D rotation effects are folded into the accumulated affine transform path, while projection and 3D rotation effects only require item-level rendering when they are non-identity.

It also restores the rotate-related UI snapshot suites for the OpenSwiftUI renderer:

• RotationEffectUITests
• Rotation3DEffectUITests
• ZStackIndexUITests.rotateOverlap

The previous merge behavior could leave rotate effects on the renderer-backed path with an incorrect view hierarchy. This keeps the affine transform state updated for 2D rotation and re-enables the matching UI coverage.

Validation

• xcrun swift build --target OpenSwiftUICore

[Kyle-Ye]

/uitest

[augmentcode]

🤖 Augment PR Summary

Summary: Fixes display-list transform merging so 2D rotations are accumulated into the affine state for the OpenSwiftUI renderer.
Changes: Non-identity projection/3D rotations now render via item-level projection views and the rotate snapshot UITest suites are re-enabled.

_{🤖 Was this summary useful? React with 👍 or 👎}

[augmentcode]

Review completed. 1 suggestion posted.

Comment augment review to trigger a new review at any time.

[augmentcode]

transform.affineTransform now includes .rotation, so state.adjust(for:) will run for arbitrary rotation matrices. adjust(for:) derives a scale factor from CGSize(width: 1, height: 1).applying(transform).width, which can be 0/negative for pure rotations (e.g. 45°/90°) and may blow up/flip inherited shadow/blur radii.

Severity: medium

_{🤖 Was this useful? React with 👍 or 👎, or 🚀 if it prevented an incident/outage.}

[codecov]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 26.95%. Comparing base (1cb2809) to head (4c634be).

Files with missing lines	Patch %	Lines
...Core/Render/DisplayList/DisplayListViewModel.swift	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #879      +/-   ##
==========================================
- Coverage   26.95%   26.95%   -0.01%     
==========================================
  Files         678      678              
  Lines       47146    47139       -7     
==========================================
- Hits        12706    12704       -2     
+ Misses      34440    34435       -5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.