Add focused XCFramework slice builds

[Kyle-Ye]

Summary

• Add a focused XCFramework slice helper for Release arm64 iPhone Simulator builds of OpenSwiftUICore and OpenSwiftUI.
• Report cache state, selected configuration, invoked command, result, and elapsed time.
• Support DerivedData reuse in the existing XCFramework builder.
• Document the focused build commands for local development.

Motivation

Full binary distribution builds cover multiple frameworks and platforms, while local implementation work often needs only one simulator slice. The focused entry point reduces unnecessary work while retaining the release build configuration.

Validation

• Validated shell syntax and linting.
• Confirmed helper argument handling, configuration logging, and failure summaries through a non-build smoke test.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 27.29%. Comparing base (1ed914d) to head (442168f).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #967       +/-   ##
===========================================
+ Coverage   15.12%   27.29%   +12.16%     
===========================================
  Files         687      730       +43     
  Lines       46487    53134     +6647     
===========================================
+ Hits         7033    14502     +7469     
+ Misses      39454    38632      -822     

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[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Cache hit rate	Tests	Skipped	Ran	Commit
OpenSwiftUI	✅	0 %	82	0	82	83260d6d7

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	2m 48s	83260d6d7