feat: add gh CLI, kubeseal CLI, and Helm MCP sidecar

Install GitHub CLI (gh) via official APT repo and kubeseal via GitHub
Releases binary in the Dockerfile. Add mcp-helm sidecar on port 8088
for AI-assisted Helm chart browsing, with corresponding values, schema,
deployment template, and .mcp.json configuration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

chart/templates/deployment.yaml

@@ -179,6 +179,29 @@ spec:
           resources:
             {{- toYaml .Values.mcp.sidecars.flux.resources | nindent 12 }}
         {{- end }}
+        {{- if .Values.mcp.sidecars.helm.enabled }}
+        - name: helm-mcp
+          image: "{{ .Values.mcp.sidecars.helm.image.repository }}:{{ .Values.mcp.sidecars.helm.image.tag }}"
+          args:
+            - -mode=sse
+            - -port={{ .Values.mcp.sidecars.helm.port }}
+          ports:
+            - containerPort: {{ .Values.mcp.sidecars.helm.port }}
+              name: helm-mcp
+              protocol: TCP
+          livenessProbe:
+            tcpSocket:
+              port: {{ .Values.mcp.sidecars.helm.port }}
+            initialDelaySeconds: 10
+            periodSeconds: 10
+          readinessProbe:
+            tcpSocket:
+              port: {{ .Values.mcp.sidecars.helm.port }}
+            initialDelaySeconds: 5
+            periodSeconds: 5
+          resources:
+            {{- toYaml .Values.mcp.sidecars.helm.resources | nindent 12 }}
+        {{- end }}
         {{- if .Values.mcp.sidecars.homeassistant.enabled }}
         - name: homeassistant-mcp
           image: "{{ .Values.mcp.sidecars.homeassistant.image.repository }}:{{ .Values.mcp.sidecars.homeassistant.image.tag }}"