SolidJS reactive UI library. Covers signals, effects, and fine-grained
reactivity.
USE WHEN: user mentions "SolidJS", "Solid", "createSignal", "createEffect", "createMemo",
"fine-grained reactivity", asks about "Solid patterns", "reactive primitives"
DO NOT USE FOR: React - use `frontend-react` (different API despite similar JSX),
Vue - use `vue-composition`, Svelte - use `svelte`, Angular - use `angular`