Follow the gateway Kustomization into the domain namespace

dependsOn still named flux-system, where the gateway Kustomization used to
live. It moved into the domain namespace so the feature team can reach it,
and a dependency naming the old location resolves to nothing — Flux
reported "dependency not found" and held this Kustomization not ready
rather than failing loudly.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

dev/flux-kustomization.yaml

@@ -12,7 +12,10 @@ spec:
   prune: true
   dependsOn:
     - name: payments-dev-api-gateway
-      namespace: flux-system
+      # The gateway Kustomization moved out of flux-system into this domain's
+      # namespace, where the team can reach it. A dependsOn that still named
+      # flux-system resolved to nothing and left this Kustomization not ready.
+      namespace: payments
   postBuild:
     substitute:
       NAME: payments-dev