chore: initial DSMMG v0.2 — refonte architecturale complète

Mise en place du Design System ManageMate Group v0.2 — refonte du
système de tokens (préfixe --mmg-color-*), 9 presets accent
user-themable validés WCAG AA, overlays Radix UI + Floating UI,
Storybook 8 + Vitest + axe-core en CI, doc Astro Starlight,
DESIGN.md (format google-labs-code) et exports tokens DTCG/CSS/
TS/Figma/Tailwind v3 et v4.

- 4 packages monorepo pnpm : @managemate/{tokens,css,react,icons}
- 62 composants React headless-first (Sheet, HoverCard, ContextMenu,
  Slider, ToggleGroup, AvatarGroup, UserCard, ProfileHeader,
  MetricCard, PricingCard, FeatureCard, Text/Display/Eyebrow/Lead…)
- Lint contraste WCAG : 37/37 paires AA, branché CI
- Toast pile Sonner-style avec ResizeObserver
- Theming user (9 presets) sans casser sémantique fixe
- Identité Synapse (rose #D12B6A) préservée

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.size-limit.json

@@ -0,0 +1,32 @@
+[
+  {
+    "name": "@managemate/react — full barrel (ESM)",
+    "path": "packages/react/dist/index.js",
+    "limit": "60 KB",
+    "ignore": ["react", "react-dom", "react/jsx-runtime"]
+  },
+  {
+    "name": "@managemate/react — single Button (tree-shake)",
+    "path": "packages/react/dist/index.js",
+    "import": "{ Button }",
+    "limit": "5 KB",
+    "ignore": ["react", "react-dom", "react/jsx-runtime"]
+  },
+  {
+    "name": "@managemate/react — Dialog + ConfirmDialog (Radix)",
+    "path": "packages/react/dist/index.js",
+    "import": "{ Dialog, ConfirmDialog }",
+    "limit": "30 KB",
+    "ignore": ["react", "react-dom", "react/jsx-runtime"]
+  },
+  {
+    "name": "@managemate/css — full bundle",
+    "path": "packages/css/dist/index.css",
+    "limit": "40 KB"
+  },
+  {
+    "name": "@managemate/icons — full bundle (192 classes)",
+    "path": "packages/icons/dist/icons.css",
+    "limit": "120 KB"
+  }
+]