fix: height graph renders correctly when reopened

[thisisharsh7]

Fixes Issue

Closes #348

What's the problem?

The height graph shows up fine the first time you open it, but if you close it and reopen it, you just get a blank SVG with the legend at the bottom.

Why does this happen?

When you close the graph, React unmounts the SVG element. When you open it again, a fresh SVG gets mounted, but the D3 drawing code doesn't run because the useEffect dependencies haven't changed.

The useEffect was watching [data, dimensions, onHighlight], so React thinks "nothing changed, skip the effect". But the SVG element itself is brand new and needs to be drawn on.

The fix

Added isExpanded to the dependency array:

-  }, [data, dimensions, onHighlight]);
+  }, [data, dimensions, onHighlight, isExpanded]);

Now when isExpanded changes from false → true, React re-runs the effect and draws the graph.

Testing

• Open height graph → works
• Close and reopen → works now
• Repeat multiple times → keeps working

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Note: This PR description was written with assistance from AI tool. The code changes and bug investigation were done by me, and I've verified the fix works as expected.

[ghost]

Preview is ready! 🚀 You can view it here: https://valhalla-app-tests.gis-ops.com/349