feat: configure Jest testing infrastructure

- Update Jest config with module name mapping for uuid and node-fetch
- Add Babel transform for mixed JS/TS support
- Configure transformIgnorePatterns for ES modules
- Add comprehensive test mocks for uuid and node-fetch
- Setup import.meta environment variables for Jest compatibility
- Increase test timeout to 30 seconds for integration tests

tests/setup.ts

@@ -20,10 +20,29 @@ Object.defineProperty(window, 'localStorage', {
 // Mock fetch
 global.fetch = jest.fn();
 
+// Mock import.meta for Jest
+Object.defineProperty(globalThis, 'import', {
+  value: {
+    meta: {
+      env: {
+        NODE_ENV: 'test',
+        VITE_COUCHDB_URL: 'http://localhost:5984',
+        VITE_COUCHDB_USERNAME: 'admin',
+        VITE_COUCHDB_PASSWORD: 'password',
+        VITE_MAILGUN_API_KEY: 'test-key',
+        VITE_MAILGUN_DOMAIN: 'test.mailgun.org',
+        VITE_MAILGUN_BASE_URL: 'https://api.mailgun.net',
+        VITE_MAILGUN_FROM_NAME: 'Test App',
+        VITE_MAILGUN_FROM_EMAIL: 'test@example.com',
+      },
+    },
+  },
+});
+
 // Setup console to avoid noise in tests
 const originalError = console.error;
 beforeAll(() => {
-  console.error = (...args: any[]) => {
+  console.error = (...args: unknown[]) => {
     if (
       typeof args[0] === 'string' &&
       args[0].includes('Warning: ReactDOM.render is deprecated')