feat(@pulse-libs/ui): design system completo compartilhado

- Atoms (10): Button, Badge, Card, GradientText, Divider, ThemeToggle + 4 3D stubs
- Molecules (3): FeatureCard, Navbar, Footer
- Organisms (4): HeroSection, FeaturesGrid, CtaBlock, StatsGrid
- Templates (3): MainLayout, MinimalLayout, PageWithSidebar
- TOKENS export: color/space/radius constants
- Re-export pattern em todos os indices
- MIT 2026 — Atomic Design · TypeScript · React 18

src/atoms/ThemeToggle.ts

@@ -0,0 +1,12 @@
+import {useState} from 'react'
+export function ThemeToggle({defaultDark=true}:{defaultDark?:boolean}) {
+  const [dark, setDark] = useState(defaultDark)
+  return (
+    <button
+      onClick={()=>{const next=!dark;setDark(next);document.documentElement.setAttribute('data-theme',next?'dark':'light')}}
+      aria-label="Toggle theme"
+      style={{position:'fixed',top:16,right:16,zIndex:9999,padding:'7px 14px',borderRadius:99,border:'none',cursor:'pointer',color:'#fff',fontWeight:700,fontFamily:'Inter,sans-serif',fontSize:'.85rem',background:dark?'linear-gradient(135deg,#2563eb,#7c3aed)':'linear-gradient(135deg,#fbbf24,#f97316)',boxShadow:'0 0 16px rgba(0,0,0,.3)',transition:'all .2s'}}>
+      {dark?'🌙':'☀️'}
+    </button>
+  )
+}