feat(fc-network): add FlowerCore.Network app (read-only pfSense plane, ADR-189)

Stand up the pfSense automation plane (Phase 0, read-only) on RKE2 as an
ArgoCD-managed workload at network.iamworkin.lan.

- namespace fc-network
- Deployment fc-network-web: localhost/fc-network-web:v20260612-0b5b049,
  imagePullPolicy Never, port 5340, /healthz probes, runAsNonRoot 1654 +
  readOnlyRootFilesystem, RWO-safe RollingUpdate (maxSurge 0/maxUnavailable 1),
  auth gate-OFF, SQLite + snapshot-store + intended-model paths under /data.
- PVC fc-network-web-data (longhorn, 2Gi): SQLite index + on-box snapshot store
  (full-fidelity raw config.xml stays on-box; service surfaces redacted only).
- Service (ClusterIP 80 -> 5340), Certificate (ClusterIssuer step-ca-acme),
  IngressRoute (network.iamworkin.lan, all methods — POST ingest is local-only).
- kustomization.yaml for local previews / single-app validation.

The ApplicationSet git generator picks this up as infra-fc-network; if it lags,
the Application is applied manually (documented pattern).

apps/fc-network/namespace.yaml

@@ -0,0 +1,8 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: fc-network
+  labels:
+    app.kubernetes.io/part-of: flowercore
+    flowercore.io/tenant-id: system
+    flowercore.io/created-by: bluejay-infra