Fix ShapeType initialization crash

[Kyle-Ye]

Summary

• Classify basic shape paths without trapping during layer rendering.
• Select and configure CALayer or CAShapeLayer for supported solid-color shapes.
• Re-enable the OpenSwiftUI clip-effect snapshot suite.

Root cause

ShapeType.init and the related shape-layer visitor helpers still called the unimplemented failure path, causing basic shape rendering and clipping to crash.

Impact

Basic rectangles, circular and rounded shapes, and supported stroked paths can now be represented by shape layers instead of terminating during rendering.

Validation

Lightweight diff validation passed. The UI test suite was not run locally.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 53 lines in your changes missing coverage. Please review.
✅ Project coverage is 14.88%. Comparing base (252f0fc) to head (06b00a8).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/OpenSwiftUICore/Shape/ShapeLayer.swift	0.00%	53 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (252f0fc) and HEAD (06b00a8). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (252f0fc)	HEAD (06b00a8)
	2	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #975       +/-   ##
===========================================
- Coverage   27.30%   14.88%   -12.42%     
===========================================
  Files         730      688       -42     
  Lines       53134    46885     -6249     
===========================================
- Hits        14506     6977     -7529     
- Misses      38628    39908     +1280     

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