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/Button.test.tsx

@@ -0,0 +1,75 @@
+import { describe, expect, it } from "vitest";
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { axe } from "vitest-axe";
+import { Button } from "./Button";
+
+describe("Button", () => {
+  it("rend le label", () => {
+    render(<Button>Continuer</Button>);
+    expect(screen.getByRole("button", { name: "Continuer" })).toBeInTheDocument();
+  });
+
+  it("appelle onClick quand cliqué", async () => {
+    const user = userEvent.setup();
+    let clicks = 0;
+    render(<Button onClick={() => clicks++}>Cliquer</Button>);
+    await user.click(screen.getByRole("button"));
+    expect(clicks).toBe(1);
+  });
+
+  it("est focusable au clavier (Tab)", async () => {
+    const user = userEvent.setup();
+    render(<Button>OK</Button>);
+    await user.tab();
+    expect(screen.getByRole("button")).toHaveFocus();
+  });
+
+  it("active onClick avec Espace ou Entrée", async () => {
+    const user = userEvent.setup();
+    let clicks = 0;
+    render(<Button onClick={() => clicks++}>Cliquer</Button>);
+    const btn = screen.getByRole("button");
+    btn.focus();
+    await user.keyboard("{Enter}");
+    await user.keyboard(" ");
+    expect(clicks).toBe(2);
+  });
+
+  it("respecte disabled", async () => {
+    const user = userEvent.setup();
+    let clicks = 0;
+    render(
+      <Button disabled onClick={() => clicks++}>
+        OK
+      </Button>,
+    );
+    await user.click(screen.getByRole("button"));
+    expect(clicks).toBe(0);
+  });
+
+  it("loading rend le bouton inactif aux clics", async () => {
+    const user = userEvent.setup();
+    let clicks = 0;
+    render(
+      <Button loading onClick={() => clicks++}>
+        OK
+      </Button>,
+    );
+    await user.click(screen.getByRole("button"));
+    expect(clicks).toBe(0);
+  });
+
+  it("n'a pas de violations axe-core (a11y)", async () => {
+    const { container } = render(
+      <>
+        <Button>Primary</Button>
+        <Button variant="ghost">Ghost</Button>
+        <Button variant="danger">Danger</Button>
+        <Button disabled>Disabled</Button>
+        <Button icon="settings-3-line" aria-label="Paramètres" />
+      </>,
+    );
+    expect(await axe(container)).toHaveNoViolations();
+  });
+});