fix(llm-serving): allow poimen namespace ingress so memory ingest works

poimen-memory could not reach any inference pod. The egress side was
already correct: NetworkPolicy poimen/poimen-memory-llm-egress permits
port 8080 to the pods labelled llm-reasoning, llm-embeddings and
llm-reranker. This policy had no matching ingress rule, so Cilium
allowed the packet out and dropped it at the destination.

The observable was a bare timeout. The request never reached vLLM, so
the predictor log stayed empty, and /health still answered because a
probe from inside the pod does not cross the policy. That made the
failure look like a hung inference engine.

Evidence, measured on 2026-10-31 against the running predictors:

  1. A probe pod in llm-serving WITH label part-of=llm-serving:
     /v1/chat/completions -> 200 in 3.1s, 8 completion tokens.
  2. The same probe pod WITHOUT that label: 8s timeout, all services.
  3. From inside poimen-memory-bfc8k: embeddings /health -> 12s
     timeout; 10.96.0.1:443 -> 8s timeout. Same-namespace traffic
     still worked, which limits the fault to this policy.
  4. memory logged "readiness: embedder probe timed out
     elapsed_ms=10000" every 60s.

All five services already serve inference correctly. They are
reasoning (3.1s), reasoning-short (2.5s), embeddings (0.5s, real
768-dim vector), reranker (0.09s, 0.982 vs 0.00004) and qwen-cpu
(4.1s, qwen2.5:3b-instruct).

This adds the missing ingress rule. It mirrors the existing paperless
rule, which bypasses the gateway for the same reason: poimen-memory
has no service-account JWT yet.

Refs: #TBD

k8s/apps/llm-serving/networkpolicy.yaml

@@ -66,6 +66,19 @@ spec:
           port: 80
         - protocol: TCP
           port: 8000
+    # Allow from poimen namespace (poimen-memory ingest + query).
+    # The client-side egress rule already exists and is not the gap:
+    # NetworkPolicy poimen/poimen-memory-llm-egress permits port 8080 to pods
+    # labelled llm-reasoning, llm-embeddings and llm-reranker. This policy had no
+    # matching ingress rule, so the packet was allowed out and dropped here.
+    # The client then sees a bare timeout and the predictor log stays empty.
+    - from:
+        - namespaceSelector:
+            matchLabels:
+              kubernetes.io/metadata.name: poimen
+      ports:
+        - protocol: TCP
+          port: 8080
     # Allow intra-namespace (pod-to-pod within llm-serving)
     - from:
         - podSelector: