Add LazyState

[Kyle-Ye]

Summary

• Add LazyState as a private SPI property wrapper with lazy initial storage, wrapped value access, projected bindings, and dynamic property installation.
• Reuse stored location state plumbing through package-scoped access needed by the OpenSwiftUI target.
• Include unavailable Sendable conformances for the wrapper and storage.

Testing

• swift build --target OpenSwiftUI

[augmentcode]

🤖 Augment PR Summary

Summary: This PR introduces a new private-SPI @LazyState property wrapper that defers computing its initial value until the state is actually installed in the dynamic property system.

Changes:

• Added LazyState (OpenSwiftUI target) with thunk-based storage, wrapped value access, and projected Binding support.
• Implemented LazyState._makeProperty and a matching LazyStatePropertyBox to integrate with _DynamicPropertyBuffer and state signaling.
• Reused existing StoredLocation plumbing to back LazyState once installed, updating the wrapper’s storage from thunk to concrete value.
• Adjusted StoredLocation/StoredLocationBase access control (e.g., updateValue, invalidate(), initializer) to package so OpenSwiftUI can use it across targets in the same SwiftPM package.
• Switched OpenAttributeGraphShims import in StoredLocation.swift to package import to align with package-scoped usage.
• Added unavailable Sendable conformances for LazyState and its internal storage to match intended concurrency semantics.

Technical Notes: The wrapper mirrors State update semantics (including GraphHost.isUpdating read tracking) while allowing the initial value closure to be skipped on repeated view re-initializations.

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[augmentcode]

Review completed. 1 suggestion posted.

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

[augmentcode]

The Log.runtimeIssues message here still says "Accessing State's value" even though this is LazyState; that can be confusing when diagnosing runtime warnings.

Severity: low

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 77 lines in your changes missing coverage. Please review.
✅ Project coverage is 26.24%. Comparing base (2ef0b16) to head (b956bd0).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/OpenSwiftUI/Data/State/LazyState.swift	0.00%	67 Missing ⚠️
...es/OpenSwiftUICore/Data/State/StoredLocation.swift	0.00%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #906      +/-   ##
==========================================
- Coverage   26.71%   26.24%   -0.47%     
==========================================
  Files         697      711      +14     
  Lines       48916    49787     +871     
==========================================
+ Hits        13068    13069       +1     
- Misses      35848    36718     +870     

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