feat(event): implement PlatformUnaryViewResponder

[Kyle-Ye]

Summary

• Add PlatformUnaryViewResponder with parent linkage and a single layout responder child.
• Forward event binding and gesture operations to the layout responder, and traverse it only when the visitor returns .next.

Validation

• Scoped macOS type checking and iOS source parsing passed.
• Passed 40 scoped behavior checks with controlled platform and gesture fixtures.

[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Ran test modules	Commit
OpenSwiftUI	✅	7	3098c441b

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	1m 20s	3098c441b

[codecov]

Codecov Report

❌ Patch coverage is 0% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 31.33%. Comparing base (b17d55b) to head (13c7f0a).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...I/Event/Responder/PlatformUnaryViewResponder.swift	0.00%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1120      +/-   ##
==========================================
- Coverage   32.80%   31.33%   -1.47%     
==========================================
  Files         823      847      +24     
  Lines       66354    69428    +3074     
==========================================
- Hits        21766    21754      -12     
- Misses      44588    47674    +3086     

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