chore(ai-guard): scale to 0 — Phase 0 stabilization per AI architecture doc

ai-guard has been in ImagePullBackOff for 14+ days: no Dockerfile exists
in its source repo so no image was ever successfully built by CI, it
has no Kubernetes Service (unreachable even if the pod were healthy),
and its own dependencies (llm-guard, presidio) were never deployed.
Nothing currently routes through it anyway — both AI consumers call
LiteLLM directly. Scaling to 0 stops the wasted pull-retry churn until
it's properly rebuilt (Phase 3 of the target architecture).

apps/ai-guard/base/deployment.yaml

@@ -1,3 +1,13 @@
+# Scaled to 0 (Phase 0 of the AI architecture doc — "Stabilize the Existing
+# Environment"): ai-guard has no Dockerfile in its source repo, so no image
+# has ever been successfully built by its CI. The pod has been in
+# ImagePullBackOff for 14+ days (90,000+ failed pulls) pulling an image that
+# doesn't exist. It also has no Service (unreachable even if healthy) and
+# depends on llm-guard/presidio, neither of which are deployed. Nothing
+# currently routes through it — both AI consumers (nxtgauge-ai-assistant,
+# nxtgauge-backend-rust) call LiteLLM directly. Scaling to 0 stops the
+# wasted kubelet pull-retry churn until Phase 3 (Rebuild ai-guard) is done
+# properly, per the architecture doc.
 apiVersion: apps/v1
 kind: Deployment
 metadata:
@@ -6,7 +16,7 @@ metadata:
   labels:
     app: ai-guard
 spec:
-  replicas: 1
+  replicas: 0
   selector:
     matchLabels:
       app: ai-guard