fix(identity): correct seed allocation and restore IdentityLink

[Kyle-Ye]

Summary

• Advance identity seeds correctly and wrap from UInt32.max to 1, preserving 0 as invalid.
• Restore IdentityLink initialization and property-wrapper reads, rejecting reads before installation.
• Add tests for distinct identities, seed overflow, and invalid reads.

[codecov]

Codecov Report

❌ Patch coverage is 16.66667% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 33.12%. Comparing base (f47dd57) to head (61977d9).

Files with missing lines	Patch %	Lines
Sources/OpenSwiftUI/View/IdentityLink.swift	16.66%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1093      +/-   ##
==========================================
+ Coverage   33.10%   33.12%   +0.01%     
==========================================
  Files         803      803              
  Lines       63662    63667       +5     
==========================================
+ Hits        21077    21090      +13     
+ Misses      42585    42577       -8     

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[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Test modules	Commit
OpenSwiftUI	✅	7	7ca4c3dd3

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	41.2s	7ca4c3dd3