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>

packages/react/src/Fab.tsx

@@ -0,0 +1,22 @@
+import type { ButtonHTMLAttributes } from "react";
+import { cx } from "./utils";
+import { Icon, type IconName } from "./Icon";
+
+export type FabProps = ButtonHTMLAttributes<HTMLButtonElement> & {
+  icon: IconName;
+  label: string;
+};
+
+export function Fab({ icon, label, className, ...rest }: FabProps) {
+  return (
+    <button
+      type="button"
+      className={cx("mmg-fab", className)}
+      aria-label={label}
+      title={label}
+      {...rest}
+    >
+      <Icon name={icon} size="lg" />
+    </button>
+  );
+}