Update GraphHost and implement global transactions

[Kyle-Ye]

Summary

• Implement global transaction coalescing and flushing, preserve queued trace identifiers, and correct continuation and deferred update behavior.
• Complete root subgraph teardown and replacement, restore the current subgraph after initialization, and correct inherited removal and preference-key handling.
• Add missing API availability annotations and regression coverage for transaction ordering, lifecycle boundaries, and context restoration.

[codecov]

Codecov Report

❌ Patch coverage is 81.31313% with 37 lines in your changes missing coverage. Please review.
✅ Project coverage is 29.59%. Comparing base (93aaeed) to head (b07e658).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
Sources/OpenSwiftUICore/Graph/GraphHost.swift	81.63%	36 Missing ⚠️
...enSwiftUICore/View/VariadicView/VariadicView.swift	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1045      +/-   ##
==========================================
+ Coverage   29.51%   29.59%   +0.07%     
==========================================
  Files         777      783       +6     
  Lines       59845    61627    +1782     
==========================================
+ Hits        17664    18239     +575     
- Misses      42181    43388    +1207     

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[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Cache hit rate	Tests	Skipped	Ran	Commit
OpenSwiftUI	✅	0 %	1136	0	1136	798895009

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	1m 30s	798895009