feat(helm): Add Prometheus configuration to Helm chart

This change adds the ability to configure the Prometheus URL via the Helm chart.

- A `prometheus` section with a `url` field has been added to `values.yaml`.
- The `configmap.yaml` template has been updated to use this value to configure the application.

Author: google-labs-jules[bot]

charts/kubernetes-mcp-server/templates/configmap.yaml

@@ -22,6 +22,10 @@ data:
       username = "{{ .Values.config.confluence.username }}"
       token = "{{ .Values.config.confluence.token }}"
     {{- end }}
+    {{- if .Values.config.prometheus.url }}
+    [prometheus]
+      url = "{{ .Values.config.prometheus.url }}"
+    {{- end }}
     {{- if .Values.config.oauth.require }}
     [oauth]
       require = {{ .Values.config.oauth.require }}

charts/kubernetes-mcp-server/values.yaml

@@ -104,6 +104,8 @@ config:
     # url: https://your-confluence-instance
     # username: user
     # token: "" # It is recommended to set this via --set-string in a CI/CD pipeline
+  prometheus:
+    # url: http://your-prometheus-instance:9090
   oauth:
     # require: false
     # audience: ""