feat(focus): implement focus state, values, and platform responders

[Kyle-Ye]

Summary

Connect focus bindings and focused values to shared stores and platform responders.

• Implement focus state bindings, focused values and bindings, and DocC comments for public focus APIs.
• Add focus stores, deferred updates, default focus evaluation, and focus view graph state.
• Connect shared focus responders and view providers on UIKit and AppKit.
• Add focusable options and interactions, UIKit hosted focus item lifecycle logging, and macOS focus ring rendering and delegation.

[codecov]

Codecov Report

❌ Patch coverage is 3.81041% with 1035 lines in your changes missing coverage. Please review.
✅ Project coverage is 30.97%. Comparing base (b17d55b) to head (8e63e2f).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/OpenSwiftUI/Event/Focus/FocusedValue.swift	3.70%	182 Missing ⚠️
Sources/OpenSwiftUI/Event/Focus/Focusable.swift	0.00%	154 Missing ⚠️
Sources/OpenSwiftUI/Event/Focus/FocusStore.swift	0.71%	138 Missing ⚠️
Sources/OpenSwiftUI/Event/Focus/FocusState.swift	0.00%	128 Missing ⚠️
Sources/OpenSwiftUI/Event/Focus/FocusItem.swift	1.75%	112 Missing ⚠️
.../OpenSwiftUI/Event/Focus/FocusEffectDelegate.swift	0.00%	53 Missing ⚠️
...rces/OpenSwiftUI/Event/Focus/FocusRingHelper.swift	0.00%	45 Missing ⚠️
...rces/OpenSwiftUI/Event/Focus/FocusEffectView.swift	0.00%	41 Missing ⚠️
...urces/OpenSwiftUI/Event/Focus/FocusStoreList.swift	0.00%	35 Missing ⚠️
...urces/OpenSwiftUI/Event/Focus/FocusViewGraph.swift	46.55%	31 Missing ⚠️
... and 14 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1119      +/-   ##
==========================================
- Coverage   32.80%   30.97%   -1.83%     
==========================================
  Files         823      860      +37     
  Lines       66354    70441    +4087     
==========================================
+ Hits        21766    21820      +54     
- Misses      44588    48621    +4033     

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[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Ran test modules	Commit
OpenSwiftUI	✅	7	e13388783

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	43.8s	e13388783