feat(plane): per-task egress policy; receiver by name through the gateway

Agent Substrate's egress gateway denies an actor without an EgressPolicy, so
no task could deliver its artifacts or reach a model. egress.py grants each
task exactly: http/80 to ousast-receiver.ax-system.svc.cluster.local, and
TLS passthrough/443 to the bound Workspaces' https Git hosts and the bound
Model's openultrasast.io/egress-hosts (api.deepseek.com for deepseek-flash).
No IPs, no wildcards, no https (MITM) rules.

The reconciler writes the policy with kubectl-ate between ax apply and
resume, reads it back, waits OUSAST_EGRESS_SETTLE (11 s, the gateway's
cached deny), and after ax delete task confirms the policy went with its
actor (kubectl-ate has no delete verb; the store cascades).

The receiver is a selector-less Service (ops/ax/receiver-service.yaml.tmpl,
applied by up.sh together with the no-build agentgateway egress gateway)
on port 18090 of the host. Measured live: the gateway checks the policy on
Host but connects to the address the actor dialled, so the runner dials the
Service's ClusterIP (OUSAST_ARTIFACT_DIAL) with the receiver's name as Host.
The runner now labels its delivery with the Run's task name (OUSAST_TASK),
which is what the receiver accepts; the ax Task name was refused with 403.
The Receiver moved to egress.py to keep reconciler.py at 460 lines.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

ops/ax/receiver-service.yaml.tmpl

@@ -0,0 +1,31 @@
+# The reconciler's artifact receiver by name (ai-service-plane task 0). Actors reach nothing but through Agent
+# Substrate's egress gateway, and the gateway allows HTTP by hostname only (never an IP address): the runner dials
+# this Service's ClusterIP on port 80 with Host `ousast-receiver.ax-system.svc.cluster.local`; the gateway allows
+# it on that Host and connects to the ClusterIP, which kube-proxy maps to the endpoint below, the host's receiver
+# on ${OUSAST_ARTIFACT_PORT} at the kind gateway. Rendered by up.sh.
+apiVersion: v1
+kind: Service
+metadata:
+  name: ousast-receiver
+  namespace: ax-system
+spec:
+  ports:
+    - name: http
+      port: 80
+      targetPort: ${OUSAST_ARTIFACT_PORT}
+      protocol: TCP
+---
+apiVersion: discovery.k8s.io/v1
+kind: EndpointSlice
+metadata:
+  name: ousast-receiver-host
+  namespace: ax-system
+  labels:
+    kubernetes.io/service-name: ousast-receiver
+addressType: IPv4
+ports:
+  - name: http
+    port: ${OUSAST_ARTIFACT_PORT}
+    protocol: TCP
+endpoints:
+  - addresses: ["${KIND_GATEWAY}"]