feat: sort modes by usage frequency

[roomote]

Summary

This PR implements mode sorting by usage frequency as requested in #5975. The most frequently used modes will now appear at the top of the mode selection list, making it easier for users to quickly access their preferred modes.

Changes

• Added mode usage tracking: Added modeUsageFrequency field to the global state schema to track how often each mode is used
• Track usage on mode switch: Updated handleModeSwitch in ClineProvider to increment usage count when switching modes
• Sort modes by frequency: Modified ModesView component to sort modes by usage frequency in descending order
• Maintain stable ordering: When modes have equal usage frequency, they maintain their original order
• Added comprehensive tests: Added tests for both the usage tracking logic and the sorting functionality

Implementation Details

• Usage frequency is stored as a simple object mapping mode slugs to usage counts
• The sorting algorithm prioritizes frequently used modes while maintaining stable ordering for modes with equal usage
• Modes with no usage data appear after modes that have been used
• The implementation is backward compatible - existing installations will start with no usage data and build it over time

Testing

• Added tests in ClineProvider.spec.ts to verify mode usage tracking
• Added tests in ModesView.spec.tsx to verify sorting behavior
• All existing tests continue to pass

Fixes #5975

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Important

This PR sorts modes by usage frequency, updating state management and UI components to enhance user experience.

• Behavior:
  • Modes are sorted by usage frequency in ModesView.tsx, with most used modes appearing first.
  • Modes with equal frequency maintain original order.
  • Modes with no usage data appear last.
• State Management:
  • Added modeUsageFrequency to ExtensionState in ExtensionStateContext.tsx.
  • Updated handleModeSwitch in ClineProvider.ts to track mode usage.
• Testing:
  • Added tests in ModesView.spec.tsx for sorting logic.
  • Added tests in ClineProvider.spec.ts for usage tracking.
• Misc:
  • Updated global-settings.ts to include modeUsageFrequency.

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[daniel-lxs]

I feel like it might be better to simply let the user order the modes in the modes list.