Update dependencies in package.json and package-lock.json; add testing scripts for Vitest, and include new packages such as supertest and vitest. Refactor Navigation component to improve event handling and cleanup, ensuring better performance and user experience. Enhance error handling in various API endpoints for PDF uploads and CSV saves, ensuring robust error propagation. Update nodemailer transport configuration for consistency across API handlers.

vitest.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: 'node',
+    setupFiles: ['./tests/setup.ts'],
+    coverage: {
+      provider: 'istanbul',
+      reporter: ['text', 'lcov'],
+      reportsDirectory: './coverage'
+    }
+  }
+})