test ✅: add comprehensive test suite for CSS ordering rules

Add tests for all three CSS property ordering rules:

    alphabetical-order,
    concentric-order,
    custom-order,

Tests cover all implemented vanilla-extract APIs, fontFace, globalFontFace, globalKeyframes, globalStyle, keyframes, style, and styleVariants.. Each test verifies both valid and invalid cases, along with proper auto-fixing functionality.

vitest.config.mjs

@@ -0,0 +1,31 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    coverage: {
+      provider: 'v8',
+      reporter: ['html', 'json', 'text'],
+      reportsDirectory: './coverage/vitest-reports',
+      //   include: ['src/**/rule-definition.ts'],
+      include: ['src/**/*.ts', '!src/**/*.test.ts', '!src/**/__tests__/**'],
+      //   exclude: [
+      //     'src/**/*.css.ts',
+      //     'src/**/*.test.ts',
+      //     'src/**/*constants.ts',
+      //     'src/**/*index.ts',
+      //     // Exclude all icon directories and their contents
+      //     'src/components/common/icons/**',
+      //     // But include the CheckboxIcon component
+      //     '!src/components/common/icons/checkbox-icon/CheckboxIcon.tsx',
+      //   ],
+    },
+    reporters: [
+      'default',
+      ['json', { outputFile: './coverage/vitest-results/vitest-results.json' }],
+      ['junit', { outputFile: './coverage/vitest-results/vitest-results.xml' }],
+    ],
+    environment: 'node',
+    include: ['src/**/*.test.ts'],
+    globals: true,
+  },
+});