fix: correct securityContext rendering in temporal Helm template

The temporal deployment template used `$security_context | nindent`
directly on a map value, causing a Helm type error. Use the same
`{{- with $security_context }} securityContext: {{- toYaml . | nindent }}
{{- end }}` pattern as the other endpoint type templates.

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

Author: lilyz-ai

charts/model-engine/templates/service_template_config_map.yaml

@@ -474,7 +474,10 @@ data:
           priorityClassName: ${PRIORITY}
           containers:
             - name: main
-              {{- $security_context | nindent 14 }}
+              {{- with $security_context }}
+              securityContext:
+                {{- toYaml . | nindent 16 }}
+              {{- end }}
               image: ${IMAGE}
               imagePullPolicy: IfNotPresent
               command: ${COMMAND}