feat: add marketplace metrics, privacy features, and service registry endpoints

- Add Prometheus metrics for marketplace API throughput and error rates with new dashboard panels
- Implement confidential transaction models with encryption support and access control
- Add key management system with registration, rotation, and audit logging
- Create services and registry routers for service discovery and management
- Integrate ZK proof generation for privacy-preserving receipts
- Add metrics instru

infra/helm/charts/monitoring/Chart.yaml

@@ -0,0 +1,19 @@
+apiVersion: v2
+name: aitbc-monitoring
+description: AITBC Monitoring Stack (Prometheus, Grafana, AlertManager)
+type: application
+version: 0.1.0
+appVersion: "0.1.0"
+dependencies:
+  - name: prometheus
+    version: 23.1.0
+    repository: https://prometheus-community.github.io/helm-charts
+    condition: prometheus.enabled
+  - name: grafana
+    version: 6.58.9
+    repository: https://grafana.github.io/helm-charts
+    condition: grafana.enabled
+  - name: alertmanager
+    version: 1.6.1
+    repository: https://prometheus-community.github.io/helm-charts
+    condition: alertmanager.enabled