feat: Migrate from Socket.IO to Server-Sent Events (SSE)

- Replace Socket.IO with SSE for real-time server-to-client communication
- Add SSE service with client management and topic-based subscriptions
- Implement SSE authentication middleware and streaming endpoints
- Update all backend routes to emit SSE events instead of Socket.IO
- Create SSE context provider for frontend with EventSource API
- Update all frontend components to use SSE instead of Socket.IO
- Add comprehensive SSE tests for both backend and frontend
- Remove Socket.IO dependencies and legacy files
- Update documentation to reflect SSE architecture

Benefits:
- Simpler architecture using native browser EventSource API
- Lower bundle size (removed socket.io-client dependency)
- Better compatibility with reverse proxies and load balancers
- Reduced resource usage for Raspberry Pi deployment
- Standard HTTP-based real-time communication

🤖 Generated with [AI Assistant]

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

Makefile

@@ -275,7 +275,6 @@ k8s-deploy: k8s-namespace-create
 	@kubectl apply -f deploy/k8s/registry-secret.yaml -n $(K8S_NAMESPACE)
 	@kubectl apply -f deploy/k8s/configmap.yaml -n $(K8S_NAMESPACE)
 	@kubectl apply -f deploy/k8s/secrets.yaml -n $(K8S_NAMESPACE) 2>/dev/null || echo "Warning: secrets.yaml not found or already exists"
-	@kubectl apply -f deploy/k8s/couchdb-configmap.yaml -n $(K8S_NAMESPACE)
 	@kubectl apply -f deploy/k8s/couchdb-statefulset.yaml -n $(K8S_NAMESPACE)
 	@kubectl apply -f deploy/k8s/backend-deployment.yaml -n $(K8S_NAMESPACE)
 	@kubectl apply -f deploy/k8s/frontend-deployment.yaml -n $(K8S_NAMESPACE)
@@ -367,4 +366,4 @@ k8s-delete:
 	@kubectl delete -f deploy/k8s/ -n $(K8S_NAMESPACE) --ignore-not-found=true
 	@echo ""
 	@echo "Resources deleted from $(K8S_NAMESPACE)"
-	@echo "Note: The namespace itself still exists. Use 'kubectl delete namespace $(K8S_NAMESPACE)' to remove it."
+	@echo "Note: The namespace itself still exists. Use 'kubectl delete namespace $(K8S_NAMESPACE)' to remove it."