Fix trajectory viewer race condition with request counter

[khaliqgant]

Summary

• Fixes trajectory viewer showing wrong data when clicking between trajectories quickly
• Adds request counter pattern to prevent stale fetch responses from overwriting newer data
• More robust than previous ID-only comparison approach

Problem

When clicking trajectories quickly, users would see:

1. Wrong trajectory data loading
2. Overview data appearing instead of specific trajectory
3. Wrong data after another click

Root cause: Stale fetch responses could complete and update state after a newer selection was made. The previous fix using trajectory ID comparison wasn't sufficient for all race conditions.

Solution

Added requestCounterRef pattern:

• Each fetch captures a unique request ID at start
• selectTrajectory() increments counter to immediately invalidate in-flight fetches
• Double-check both request ID AND trajectory ID before updating state
• Early return when clicking same trajectory (prevents redundant fetches)
• Only update error state if request is still current

Test plan

• Open trajectory panel with multiple trajectories in history
• Click rapidly between different trajectories
• Verify correct trajectory data loads each time
• Check console for "[useTrajectory] Ignoring superseded fetch" logs confirming stale data blocked
• Click same trajectory twice - should not re-fetch

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📊 1 file reviewed • 6 need attention

⚠️ Needs Attention:

• src/dashboard/react-components/hooks/useTrajectory.ts — Significant concerns regarding error handling and request counter management which could impact data integrity and user feedback.

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