feat(gesture): implement DragGesture

[Kyle-Ye]

Summary

Close #1153

• Implement DragGesture and DragGesture.Value, including translation, velocity, and predicted end values, with public documentation.
• Start a drag only after it moves the minimum distance, using touch events on iOS and visionOS and mouse events on macOS.
• Add _EventDirections and CGSize magnitude and normalization helpers used to measure drag movement.
• Add a drag example, a drag helper for the interaction test host, and interaction tests for translation and minimum distance.
• Update Hammer to 0.19.3 so synthetic macOS drags start at the requested location.

Validation

• Drag gesture interaction tests pass with SwiftUI and OpenSwiftUI on macOS, including the minimum-distance case.

Dependency

• OpenSwiftUIProject/Hammer#2 (merged, released in 0.19.3)

[tuist]

🛠️ Tuist Run Report 🛠️

Tests 🧪

Scheme	Status	Ran test modules	Commit
Unknown	⏳	7	19aab218e
OpenSwiftUI	✅	7	19aab218e

Builds 🔨

Scheme	Status	Duration	Commit
OpenSwiftUI	✅	44.6s	19aab218e

[codecov]

Codecov Report

❌ Patch coverage is 0% with 104 lines in your changes missing coverage. Please review.
✅ Project coverage is 29.51%. Comparing base (ee1cf1d) to head (ce264cd).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
...ources/OpenSwiftUI/Event/Gesture/DragGesture.swift	0.00%	78 Missing ⚠️
...es/OpenSwiftUI/Event/Gesture/EventDirections.swift	0.00%	13 Missing ⚠️
...s/OpenSwiftUICore/Util/Extension/CGSize+Math.swift	0.00%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1168      +/-   ##
==========================================
- Coverage   30.43%   29.51%   -0.92%     
==========================================
  Files         913      941      +28     
  Lines       71182    74552    +3370     
==========================================
+ Hits        21662    22007     +345     
- Misses      49520    52545    +3025     

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[Kyle-Ye]

/interactiontest osui-iag update only-testing=OpenSwiftUIInteractionTests/DragGestureInteractionTests