feat: Complete CouchDB test infrastructure migration for route tests

- Fixed 5/7 route test suites (auth, events, reports, rewards, streets)
- Updated Jest configuration with global CouchDB mocks
- Created comprehensive test helper utilities with proper ID generation
- Fixed pagination response format expectations (.data property)
- Added proper model method mocks (populate, save, toJSON, etc.)
- Resolved ID validation issues for different entity types
- Implemented proper CouchDB service method mocking
- Updated test helpers to generate valid IDs matching validator patterns

Remaining work:
- posts.test.js: needs model mocking and response format fixes
- tasks.test.js: needs Task model constructor fixes and mocking

🤖 Generated with [AI Assistant]

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

backend/__tests__/utils/idGenerator.js

@@ -0,0 +1,41 @@
+/**
+ * Utility functions for generating test IDs
+ * Replaces mongoose.Types.ObjectId() functionality
+ */
+
+/**
+ * Generate a random test ID string
+ * Format: random alphanumeric string (24 characters like MongoDB ObjectId)
+ */
+function generateTestId() {
+  const chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
+  let result = '';
+  for (let i = 0; i < 24; i++) {
+    result += chars.charAt(Math.floor(Math.random() * chars.length));
+  }
+  return result;
+}
+
+/**
+ * Generate a test ID with a specific prefix
+ */
+function generateTestIdWithPrefix(prefix) {
+  return `${prefix}_${generateTestId()}`;
+}
+
+/**
+ * Generate multiple unique test IDs
+ */
+function generateTestIds(count) {
+  const ids = [];
+  for (let i = 0; i < count; i++) {
+    ids.push(generateTestId());
+  }
+  return ids;
+}
+
+module.exports = {
+  generateTestId,
+  generateTestIdWithPrefix,
+  generateTestIds,
+};