reworked struct array example

[Spiri0]

#30394 #30487

I recreated the PR because I had big problems with creating the screenshot and the branch was completely destroyed as a result. I was only able to create the screenshot with changes in puppeteer.js and the screenshot still doesn't fit.
The code itself works perfectly. @sunag you have a new node in mind for the structArray anyway. That's why I'm holding off on experimenting with screenshots for the moment

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.42 78.33	336.42 78.33	+0 B +0 B
WebGPU	518.01 143.8	518.2 143.84	+188 B +47 B
WebGPU Nodes	517.48 143.69	517.66 143.73	+188 B +46 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	465.41 112.17	465.41 112.17	+0 B +0 B
WebGPU	589.88 159.76	590.01 159.79	+122 B +26 B
WebGPU Nodes	545.25 149.23	545.37 149.26	+122 B +27 B

[Spiri0]

@sunag Is there a way to update parts of a storageBufferAttribute from the CPU side?
The advantage of the CPU is that it can pre-calculate geometries with 64bit precision
That's my naive thought, but that doesn't work.

positionBuffer.array.set( instancePositions, instanceSlot * instancePositions.length );
positionBuffer.needsUpdate = true;

I also had an example with interleaved buffers in mind but that would be a bit more extensive.