bug(knowledge-graph): Three.js GPU resources not disposed on KnowledgeGraph3D unmount

[mrveiss]

Summary

When the user toggles 2D→3D→2D repeatedly, the KnowledgeGraph3D component does not dispose Three.js GPU-allocated resources (geometry, materials, textures, renderer) when it unmounts. Each toggle cycle leaks WebGL memory until the browser tab runs out of GPU memory or crashes.

Root Cause

The original onUnmounted hook only called graph.pauseAnimation() but did not traverse the scene tree to dispose objects. Three.js requires explicit disposal:

graph.scene()?.traverse((obj) => {
  obj.geometry?.dispose()
  for (const mat of [obj.material].flat().filter(Boolean)) {
    for (const v of Object.values(mat)) {
      if (v?.isTexture) v.dispose()
    }
    mat.dispose()
  }
})
graph.renderer()?.dispose()

Impact

• GPU memory grows unboundedly on each 2D↔3D toggle
• Observed on any browser with WebGL support
• Eventual tab crash in long-running sessions

Fix

Implemented full scene traversal disposal pattern in KnowledgeGraph3D.vue onUnmounted.

Already fixed in: PR #3372 (fix: code-review issues for 3D view toggle)

References

• PR feat(knowledge-graph): add 3D force-graph view toggle (#3330) #3359 (original implementation)
• PR fix(knowledge-graph): code-review fixes for 3D view toggle (#3330) #3372 (fix)
• Issue feat(knowledge-graph): add 3D force-graph view toggle to KnowledgeGraph.vue #3330 (parent feature)