feat: add missing project files and fix architecture compliance

- Add LICENSE file (MIT)
- Add CONTRIBUTING.md with generator-first workflow guidelines
- Add Makefile with comprehensive development commands
- Add .editorconfig for consistent code formatting
- Add CHANGELOG.md for version tracking
- Remove inconsistent non-variant files that bypassed generator architecture
- Fix installation script to use variant-specific paths (prevent config overwriting)

playwright.config.js

@@ -0,0 +1,36 @@
+import { defineConfig, devices } from '@playwright/test';
+
+export default defineConfig({
+  testDir: './tests',
+  fullyParallel: true,
+  forbidOnly: !!process.env.CI,
+  retries: process.env.CI ? 2 : 0,
+  workers: process.env.CI ? 1 : undefined,
+  reporter: 'html',
+  use: {
+    baseURL: 'http://localhost:3000',
+    trace: 'on-first-retry',
+    screenshot: 'only-on-failure',
+  },
+
+  projects: [
+    {
+      name: 'chromium',
+      use: { ...devices['Desktop Chrome'] },
+    },
+    {
+      name: 'firefox',
+      use: { ...devices['Desktop Firefox'] },
+    },
+    {
+      name: 'webkit',
+      use: { ...devices['Desktop Safari'] },
+    },
+  ],
+
+  webServer: {
+    command: 'npm run demo',
+    url: 'http://localhost:3000',
+    reuseExistingServer: !process.env.CI,
+  },
+});