Scope index store workaround to system modules

[Kyle-Ye]

Summary

• add -index-ignore-system-modules to shared macOS Swift settings
• remove broader --disable-index-store overrides from macOS CI and the Stdout renderer
• document the consolidated Xcode 26.6 workaround

Motivation

Swift 6.3.3 can crash while indexing AppKit with the private framework shims. Disabling the entire index store avoids the crash, but also disables OpenSwiftUI source indexing and does not cover Xcode GUI package builds.

Applying the narrower driver flag through Package.swift skips imported system-module indexing while preserving source indexing across SwiftPM CLI, CI, the Stdout example, and Xcode GUI builds.

Validation

• validated the package manifest with Xcode 26.6
• parsed the updated workflow YAML and checked the Stdout script syntax
• built and ran the Stdout renderer example with Xcode 26.6 / Swift 6.3.3

[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Cache hit rate	Tests	Skipped	Ran	Commit
OpenSwiftUI	✅	0 %	1014	0	1014	6e112bb80

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	1m 17s	6e112bb80

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 26.29%. Comparing base (1c4edfb) to head (7e140c7).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #998      +/-   ##
==========================================
+ Coverage   26.24%   26.29%   +0.04%     
==========================================
  Files         734      734              
  Lines       55580    55580              
==========================================
+ Hits        14588    14615      +27     
+ Misses      40992    40965      -27     

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