infra(k8s): add NetworkPolicy for paper-backfill Job (DNS + 5432->postgres)

The Job failed with ConnectionTimeout — default-deny-all blocks egress and
part-of/argo-base-egress only opens DNS+443, not Postgres 5432. Add a dedicated
netpol (mirrors fxhnt-factory/forward) granting DNS + 5432->postgres. The exec
path worked only because it ran inside the dagster pod (which has its own netpol).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

infra/k8s/jobs/fxhnt-paper-backfill-job.yaml

@@ -14,9 +14,10 @@
 # the dagster pod (topologyKey hostname) co-locates automatically and survives node recycling (no hardcoded
 # nodeName). Reads the warehouse (closes) + writes Postgres (paper_*) only — no DuckDB write contention.
 #
-# EGRESS: the `app.kubernetes.io/part-of: foxhunt` POD label is REQUIRED — the namespace has default-deny-all
-# egress; that label grants `argo-base-egress` (DNS + internal CIDRs), which is all this Job needs (Postgres
-# is internal; no external fetches). Without it the backfill hangs on DB connect.
+# EGRESS: the namespace has default-deny-all egress. `argo-base-egress` (via the part-of label) only opens
+# DNS + 443 — NOT Postgres' 5432 — so this Job needs its OWN NetworkPolicy granting DNS + 5432→postgres
+# (mirrors fxhnt-factory/fxhnt-forward). The `--days 3` exec worked only because it ran INSIDE the dagster
+# pod, which already has the dagster netpol. Bundled below. No external egress needed (warehouse is a local PVC).
 apiVersion: batch/v1
 kind: Job
 metadata:
@@ -64,3 +65,20 @@ spec:
       volumes:
         - name: surfer-data
           persistentVolumeClaim: { claimName: fxhnt-surfer-data }
+---
+# Egress for the backfill Job: DNS + Postgres 5432 (internal). default-deny-all blocks all egress; the shared
+# argo-base-egress only opens DNS + 443, so this Job needs its own 5432→postgres rule (same minimal shape as
+# the fxhnt-factory / fxhnt-forward netpols). No external egress — the warehouse is a local PVC.
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: fxhnt-paper-backfill
+  namespace: foxhunt
+  labels: { app.kubernetes.io/part-of: foxhunt }
+spec:
+  podSelector: { matchLabels: { app.kubernetes.io/name: fxhnt-paper-backfill } }
+  policyTypes: [Egress]
+  egress:
+    - ports: [{ port: 53, protocol: UDP }, { port: 53, protocol: TCP }]
+    - ports: [{ port: 5432, protocol: TCP }]
+      to: [{ podSelector: { matchLabels: { app.kubernetes.io/name: postgres } } }]