Add the ability to control the simulation from JS

[alexjilkin]

• Issue related

• Similarly to Atomify, added fix js/async that hooks LAMMPS end‑of‑step/minimization and calls back into JS via Asyncify, blocking the simulation until the Promise resolves. Differently, there is no patch into lammps code so it doesn't expose additional data Atomify did, just the currently existing particles, bonds and box.
• Callback returns simulation snapshots by default (particles/bonds/box), with options to trim payloads, and supports changing the callback frequency on the fly.
• runScriptWithAsyncCallback injects the fix before the first run so scripts can stay “run N” without manual fix lines.

ThreeJS example

• Three.js demo now uses the async callback flow and a live “steps per callback” speed control.

Dist packaging

• Build emits dist/cpp/lammps.js, dist/client.js, and all .d.ts directly into dist/ (no copy step).