feat(artifactapi): migrate Ingress to Gateway API (#129)

## Summary

- Replace `Ingress` (nginx) with `Gateway` + `HTTPRoute` using `traefik-internal` GatewayClass
- TLS terminated at the Gateway listener; cert-manager provisions the certificate via `vault-issuer`
- external-dns annotations moved to the Gateway

## Notes

The original Ingress had nginx-specific annotations (`proxy-body-size: 10g`, `proxy-read-timeout: 600`) which are not portable to Gateway API. These can be re-introduced via a Traefik `Middleware` CRD if needed.

## Test plan

- [ ] ArgoCD syncs the app cleanly
- [ ] cert-manager issues the `artifactapi-tls` certificate
- [ ] external-dns creates the DNS record
- [ ] `https://artifactapi.k8s.syd1.au.unkin.net` is reachable

Reviewed-on: #129

apps/base/artifactapi/gateway.yaml

@@ -0,0 +1,29 @@
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  labels:
+    traefik.io/instance: internal
+  annotations:
+    cert-manager.io/cluster-issuer: vault-issuer
+    cert-manager.io/common-name: artifactapi.k8s.syd1.au.unkin.net
+    cert-manager.io/private-key-size: "4096"
+    external-dns.alpha.kubernetes.io/hostname: artifactapi.k8s.syd1.au.unkin.net
+    external-dns.alpha.kubernetes.io/target: 198.18.200.4
+  name: artifactapi
+  namespace: artifactapi
+spec:
+  gatewayClassName: traefik-internal
+  listeners:
+    - allowedRoutes:
+        namespaces:
+          from: Same
+      hostname: artifactapi.k8s.syd1.au.unkin.net
+      name: https
+      port: 443
+      protocol: HTTPS
+      tls:
+        certificateRefs:
+          - kind: Secret
+            name: artifactapi-tls
+        mode: Terminate

apps/base/artifactapi/httproute.yaml

@@ -0,0 +1,20 @@
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: artifactapi
+  namespace: artifactapi
+spec:
+  hostnames:
+    - artifactapi.k8s.syd1.au.unkin.net
+  parentRefs:
+    - name: artifactapi
+      sectionName: https
+  rules:
+    - backendRefs:
+        - name: artifactapi-api
+          port: 80
+      matches:
+        - path:
+            type: PathPrefix
+            value: /

apps/base/artifactapi/ingress.yaml

@@ -1,32 +0,0 @@
----
-apiVersion: networking.k8s.io/v1
-kind: Ingress
-metadata:
-  annotations:
-    cert-manager.io/cluster-issuer: vault-issuer
-    cert-manager.io/common-name: artifactapi.k8s.syd1.au.unkin.net
-    cert-manager.io/private-key-size: "4096"
-    external-dns.alpha.kubernetes.io/hostname: artifactapi.k8s.syd1.au.unkin.net
-    external-dns.alpha.kubernetes.io/target: 198.18.200.0
-    nginx.ingress.kubernetes.io/proxy-body-size: 10g
-    nginx.ingress.kubernetes.io/proxy-read-timeout: "600"
-    nginx.ingress.kubernetes.io/ssl-redirect: "false"
-  name: artifactapi-ingress
-  namespace: artifactapi
-spec:
-  ingressClassName: nginx
-  rules:
-    - host: artifactapi.k8s.syd1.au.unkin.net
-      http:
-        paths:
-          - backend:
-              service:
-                name: artifactapi-api
-                port:
-                  number: 80
-            path: /
-            pathType: Prefix
-  tls:
-    - hosts:
-        - artifactapi.k8s.syd1.au.unkin.net
-      secretName: artifactapi-tls

apps/base/artifactapi/kustomization.yaml

@@ -6,7 +6,8 @@ resources:
   - artifactapi-deployment.yaml
   - artifactapi-hpa.yaml
   - configmap.yaml
-  - ingress.yaml
+  - gateway.yaml
+  - httproute.yaml
   - namespace.yaml
   - postgres-deployment.yaml
   - pvc.yaml