Add ArcadeLab

[mlapeter]

Adding ArcadeLab to Tools > Online.

ArcadeLab is a free no-signup hosting platform for single-file HTML creative coding work — generative art sketches, physics simulations, interactive visualizations, animated explainers. Paste a complete HTML file at arcadelab.ai/publish, get a permanent shareable URL.

Why it fits the list:

• Designed specifically for the single-HTML-file format that creative coding often produces (p5.js, three.js, D3, Canvas, WebGL all work natively)
• Sibling-spirit to OpenProcessing / ShaderGif / NEORT (which are already in the Online section) — community gallery for creative output
• One concrete example of what kind of work it hosts: an interactive double-slit experiment demo
• Free, open source (github.com/mlapeter/arcadelab), no account or email required to publish

Added at the bottom of Tools > Online per CONTRIBUTING.md. Followed the format [Name](link) - Description. with capitalized start and trailing period. Single PR for the single suggestion.

Thanks for maintaining the list!