feat: enhance validation schemas with comprehensive tests for user roles, settings, exams, and collections

backend/vitest.config.ts

@@ -3,5 +3,7 @@ import { defineConfig } from 'vitest/config'
 export default defineConfig({
   test: {
     setupFiles: ['./vitest.setup.ts'],
+    include: ['src/**/*.{test,spec}.{ts,tsx}'],
+    exclude: ['node_modules', 'dist'],
   },
 })