add ghp (GitHub proxy) deployment

Deploy goodtune/ghp so estate agents have a GitHub proxy. Mirrors the
artifactapi app structure under apps/base/ghp with a CNPG Postgres backend,
VSO-synced GitHub App + encryption secrets, an internal Vault-PKI serving cert,
a PreSync migration hook, and platform ApplicationSet/project registration.

apps/base/ghp/httproute.yaml

@@ -0,0 +1,29 @@
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: ghp-route
+  namespace: ghp
+spec:
+  hostnames:
+    - ghp.k8s.syd1.au.unkin.net
+  parentRefs:
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: ghp
+      sectionName: http
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: ghp
+      sectionName: https
+  rules:
+    - backendRefs:
+        - group: ""
+          kind: Service
+          name: ghp
+          port: 80
+          weight: 1
+      matches:
+        - path:
+            type: PathPrefix
+            value: /