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/.release-please-config.json

@@ -0,0 +1,9 @@
+{
+    "packages": {
+        ".": {
+            "release-type": "node",
+            "package-name": "nodemailer",
+            "pull-request-title-pattern": "chore${scope}: release ${version} [skip-ci]"
+        }
+    }
+}