Fix trajectory viewer loading wrong data due to race condition

[khaliqgant]

Summary

• Fixes race condition where selecting a trajectory displays wrong data
• Root cause: Initial fetch with null ID could complete after selected trajectory's fetch, overwriting correct data
• Added latestSelectionRef to track current selection and ignore stale fetches

Technical Details

When the user opened the trajectory panel and quickly clicked a trajectory:

1. Initial fetch (null ID) started
2. User clicked trajectory A
3. Fetch for trajectory A started and completed
4. Initial fetch completed and overwrote A's data with null's data

The fix:

1. latestSelectionRef tracks the most recent trajectory selection
2. selectTrajectory() updates the ref immediately (synchronously, before state update)
3. fetchSteps() checks if the fetched ID matches latestSelectionRef.current before updating state
4. Stale fetches are logged and discarded

Test plan

• Open trajectory panel
• Quickly click a trajectory from the list
• Verify the correct trajectory's steps are displayed (not the initial/default)
• Click different trajectories and verify each displays correctly

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📊 1 file reviewed • 3 need attention

⚠️ Needs Attention:

• src/dashboard/react-components/hooks/useTrajectory.ts — Improvements to state management introduce potential logic and error handling concerns that need careful validation.

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