Remove repo-local dual test skill

[Kyle-Ye]

Summary

• Remove the repo-local .claude/skills/add-dual-test-case skill now that its guidance lives in the shared OpenSwiftUI workflow skill.

Testing

• Not run; documentation/skill cleanup only.

[augmentcode]

🤖 Augment PR Summary

Summary: This PR removes the repository-local Claude skill for adding DualTests now that the guidance is maintained in the shared OpenSwiftUI workflow.

Changes:

• Deleted .claude/skills/add-dual-test-case/SKILL.md containing the DualTests rules and templates
• Consolidated maintenance of this guidance into the shared workflow skill to avoid duplication/drift

Technical Notes: No production or test code changes; this is a documentation/automation cleanup.

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[augmentcode]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 14.41%. Comparing base (8b4076e) to head (114d7f6).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #853   +/-   ##
=======================================
  Coverage   14.41%   14.41%           
=======================================
  Files         634      634           
  Lines       39006    39006           
=======================================
+ Hits         5621     5623    +2     
+ Misses      33385    33383    -2     

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