cyberchef: seccompProfile RuntimeDefault in the pod context

Sets seccompProfile.type: RuntimeDefault in the pod security context, so
the container runtime's default syscall filter applies to every container
in the pod. Verified in k3d: /proc/1/status reports Seccomp: 2 (filter
mode) with one filter loaded, and nginx keeps serving the app.

The value lives in the pod context rather than the container context
because it covers init containers and any container added later without
being repeated; a container that needs a different filter can still
override it under securityContext.container, which wins over the pod
value.

Major bump: runtime behavior changes, even though it stays invisible for
this workload.

Refs #84

cyberchef/templates/_helpers.tpl

@@ -214,7 +214,8 @@ default probe needs no further context.
 {{- $defaults := dict
       "runAsNonRoot" true
       "runAsUser" 101
-      "runAsGroup" 101 -}}
+      "runAsGroup" 101
+      "seccompProfile" (dict "type" "RuntimeDefault") -}}
 {{- include "cyberchef.defaultedDict" (dict "defaults" $defaults "given" $given "path" "cyberchef.securityContext.pod") -}}
 {{- end -}}