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>

storybook/stories/Tooltip.stories.tsx

@@ -0,0 +1,47 @@
+import type { Meta, StoryObj } from "@storybook/react";
+import { Tooltip, TooltipProvider, Button } from "@managemate/react";
+
+const meta = {
+  title: "Overlays/Tooltip",
+  component: Tooltip,
+  tags: ["autodocs"],
+  decorators: [
+    (Story) => (
+      <TooltipProvider>
+        <Story />
+      </TooltipProvider>
+    ),
+  ],
+  parameters: {
+    docs: {
+      description: {
+        component:
+          "Tooltip basé sur Radix UI. Auto-flip, focus management, Escape, prefers-reduced-motion. Exige `<TooltipProvider>` à la racine.",
+      },
+    },
+  },
+} satisfies Meta<typeof Tooltip>;
+
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+export const Default: Story = {
+  args: { content: "Action sécurisée" },
+  render: (args) => (
+    <Tooltip {...args}>
+      <Button variant="ghost">Survoler ou focus</Button>
+    </Tooltip>
+  ),
+};
+
+export const Placements: Story = {
+  render: () => (
+    <div style={{ display: "flex", gap: 24, justifyContent: "center", padding: 80 }}>
+      {(["top", "right", "bottom", "left"] as const).map((p) => (
+        <Tooltip key={p} content={`Position ${p}`} placement={p}>
+          <Button variant="ghost">{p}</Button>
+        </Tooltip>
+      ))}
+    </div>
+  ),
+};