Revert "refactor: convert vitest.config to async configuration loading"

This reverts commit 98be5cd.

Author: adamrefaey

backend/vitest.config.ts

@@ -1,17 +1,14 @@
 import { defineConfig } from 'vitest/config';
+import tsconfigPaths from 'vite-tsconfig-paths';
 
-export default defineConfig(async () => {
-  const tsconfigPaths = (await import('vite-tsconfig-paths')).default;
-
-  return {
-    plugins: [tsconfigPaths()],
-    test: {
-      globals: true,
-      environment: 'node',
-      include: ['**/*.spec.ts'],
-      coverage: {
-        reporter: ['text', 'json', 'html'],
-      },
+export default defineConfig({
+  plugins: [tsconfigPaths()],
+  test: {
+    globals: true,
+    environment: 'node',
+    include: ['**/*.spec.ts'],
+    coverage: {
+      reporter: ['text', 'json', 'html'],
     },
-  };
-});
+  },
+});