joel-jain/particle-simulator — reverse-engineered prompt

Build me a simple browser based fluid particle simulator that runs from one HTML file. I want to open it in a normal browser and see lots of tiny particles moving in a smooth flowing way, almost like liquid or smoke.

Make it interactive so when I move or drag the mouse across the canvas, the particles react and swirl around the pointer. Add a small control so I can change how many particles are on screen, and make the animation update in real time without needing any external libraries or internet connection.

Keep the design clean and minimal, with the canvas filling the page and the controls easy to understand. Use plain HTML, CSS, and JavaScript only. It should work offline by just opening index.html, and the code should be simple enough that I can tweak colors, speed, and particle count later.