feat: track expand/collapse scope/variable usage

[barinali]

Proposed Changes

This pull request aims to introduce a tracking event for the collapse/expand scope/variable action.

Event Name	Action
collapseScope	User collapses a scope section
expandScope	User expands a scope section
collapseVariable	User collapses a variable row
expandVariable	User expands a variable row

Checklist

Ensure you provide everything we need to review your contribution:

• Contribution meets our definition of done
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  • Link to related issue(s), i.e. Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}
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[Copilot]

Pull request overview

This PR adds analytics tracking for user expand/collapse interactions in the variable outline UI, leveraging the existing useTracking() hook to emit namespaced events.

Changes:

• Emit expandScope / collapseScope tracking events when toggling a scope via useScopeExpand.
• Emit expandVariable / collapseVariable tracking events when toggling individual variable rows in Scope.
• Add unit tests covering the new tracking behavior and document the change in the changelog.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
lib/hooks/useScopeExpand.js	Adds scope expand/collapse tracking on toggle via useTracking()
lib/hooks/test/useScopeExpand.spec.jsx	New tests verifying expandScope / collapseScope events are fired
lib/components/Scope/Scope.jsx	Adds variable row expand/collapse tracking on per-row toggle
lib/components/Scope/test/Scope.spec.jsx	New tests verifying expandVariable / collapseVariable events are fired
CHANGELOG.md	Notes the new tracking feature in Unreleased section

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