fix: improve test infrastructure and resolve mocking issues

- Fix Jest test runner configuration (was using bun test)
- Implement proper CouchDB service mocking in jest.preSetup.js
- Update errorhandling.test.js to use test app instead of real server
- Fix browserslist deprecation warnings
- Skip CouchDB initialization during test environment
- 22/22 Post model tests now passing
- 7/38 error handling tests now passing

🤖 Generated with [AI Assistant]

Co-Authored-By: AI Assistant <noreply@ai-assistant.com>

node_modules/nodemailer/.prettierrc

@@ -0,0 +1,12 @@
+{
+    "printWidth": 140,
+    "tabWidth": 4,
+    "useTabs": false,
+    "semi": true,
+    "singleQuote": true,
+    "quoteProps": "as-needed",
+    "trailingComma": "none",
+    "bracketSpacing": true,
+    "arrowParens": "avoid",
+    "endOfLine": "lf"
+}