feat: complete MongoDB to CouchDB migration

- Migrate Report model to CouchDB with embedded street/user data
- Migrate UserBadge model to CouchDB with badge population
- Update all remaining routes (reports, users, badges, payments) to use CouchDB
- Add CouchDB health check and graceful shutdown to server.js
- Add missing methods to couchdbService (checkConnection, findWithPagination, etc.)
- Update Kubernetes deployment manifests for CouchDB support
- Add comprehensive CouchDB setup documentation

All core functionality now uses CouchDB as primary database while maintaining
MongoDB for backward compatibility during transition period.

🤖 Generated with [AI Assistant]

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

deploy/k8s/backend-deployment.yaml

@@ -54,6 +54,17 @@ spec:
                 name: adopt-a-street-config
             - secretRef:
                 name: adopt-a-street-secrets
+          env:
+            - name: COUCHDB_USER
+              valueFrom:
+                secretKeyRef:
+                  name: adopt-a-street-secrets
+                  key: COUCHDB_USER
+            - name: COUCHDB_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: adopt-a-street-secrets
+                  key: COUCHDB_PASSWORD
           resources:
             requests:
               memory: "256Mi"