[WIP] Docs: Add reference entries for p5.strands hooks (feedback wanted)

[Abhayaj247]

This draft PR adds new JSDoc reference entries for a few p5.strands hooks, following the feedback in #7919.

• The new doc comments use JavaScript-only examples and describe the callback signature as discussed.

• I’ve included examples for :

• getWorldInputs

• combineColors

• getPointSize

• The doc comments are currently placed in a new file :

src/webgl/p5.strands.js

(Open to moving them if you prefer a different location.)

Could you please review the style, level of detail, and file location?

Once confirmed, I’ll update the rest of the hooks in the same format.

Thanks for your guidance!

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