refactor: drop istio mesh egress, use cilium FQDN for znc egress filtering

Istio ambient cannot do hostname-based egress filtering without L7
processing (waypoint/sidecar). Cilium FQDN CiliumNetworkPolicy is the
right tool — DNS-aware L3/L4 enforcement.

- Remove waypoint deployment and namespace/service label references
- Move TheLounge HTTPRoute back to Cilium external gateway
- Add CiliumNetworkPolicy for znc: allow DNS + irc.passthepopcorn.me:6697
- Remove orphaned znc/egress.yaml (Istio VirtualService routing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

znc/ciliumnetworkpolicy.yaml

@@ -0,0 +1,27 @@
+apiVersion: cilium.io/v2
+kind: CiliumNetworkPolicy
+metadata:
+  name: znc-egress
+  namespace: irc
+spec:
+  endpointSelector:
+    matchLabels:
+      app.kubernetes.io/name: znc
+  egress:
+  - toEndpoints:
+    - matchLabels:
+        k8s:io.kubernetes.pod.namespace: kube-system
+        k8s:k8s-app: kube-dns
+    toPorts:
+    - ports:
+      - port: "53"
+        protocol: ANY
+      rules:
+        dns:
+        - matchPattern: "*"
+  - toFQDNs:
+    - matchName: "irc.passthepopcorn.me"
+    toPorts:
+    - ports:
+      - port: "6697"
+        protocol: TCP