Initial scaffold: React 19 + Vite + TypeScript + Tailwind CSS v4 + Storybook 10

Design system and component library for the Research Synthesiser. Includes:
- Tailwind CSS v4 with @theme-based design tokens from the existing synthesiser
- Storybook 10.4 with MCP, a11y, docs, and vitest addons
- ESLint + Prettier with Tailwind class sorting
- Button component as pipeline validation
- CLAUDE.md with project principles and conventions
- ARCHITECTURE.md as living architecture document
- Penpot and Storybook MCP server configuration

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vite.config.ts

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+/// <reference types="vitest/config" />
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+import tailwindcss from '@tailwindcss/vite';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { storybookTest } from '@storybook/addon-vitest/vitest-plugin';
+import { playwright } from '@vitest/browser-playwright';
+const dirname = typeof __dirname !== 'undefined' ? __dirname : path.dirname(fileURLToPath(import.meta.url));
+
+// More info at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon
+export default defineConfig({
+  plugins: [react(), tailwindcss()],
+  resolve: {
+    alias: {
+      '@': '/src'
+    }
+  },
+  test: {
+    projects: [{
+      extends: true,
+      plugins: [
+      // The plugin will run tests for the stories defined in your Storybook config
+      // See options at: https://storybook.js.org/docs/next/writing-tests/integrations/vitest-addon#storybooktest
+      storybookTest({
+        configDir: path.join(dirname, '.storybook')
+      })],
+      test: {
+        name: 'storybook',
+        browser: {
+          enabled: true,
+          headless: true,
+          provider: playwright({}),
+          instances: [{
+            browser: 'chromium'
+          }]
+        }
+      }
+    }]
+  }
+});