feat: move artifactapi to image-updater ApplicationSet with annotations

Moves artifactapi out of platform-apps ApplicationSet and into a dedicated
image-updater-apps ApplicationSet so image updater annotations are scoped
only to artifactapi. Reserves apps/overlays/*/argocd-image-updater in
platform-apps for the image updater deployment (followup).

argocd/applicationsets/imageupdater.yaml

@@ -0,0 +1,36 @@
+---
+apiVersion: argoproj.io/v1alpha1
+kind: ApplicationSet
+metadata:
+  name: image-updater-apps
+  namespace: argocd
+spec:
+  generators:
+  - git:
+      repoURL: https://git.unkin.net/unkin/argocd-apps
+      revision: HEAD
+      directories:
+      - path: apps/overlays/*/artifactapi
+  template:
+    metadata:
+      name: 'platform-{{path[3]}}'
+      annotations:
+        argocd-image-updater.argoproj.io/image-list: "artifactapi=git.unkin.net/unkin/artifactapi"
+        argocd-image-updater.argoproj.io/artifactapi.update-strategy: semver
+        argocd-image-updater.argoproj.io/write-back-method: git
+        argocd-image-updater.argoproj.io/git-branch: main
+    spec:
+      project: platform
+      source:
+        repoURL: https://git.unkin.net/unkin/argocd-apps
+        targetRevision: HEAD
+        path: '{{path}}'
+      destination:
+        server: https://kubernetes.default.svc
+        namespace: '{{path[3]}}'
+      syncPolicy:
+        automated:
+          prune: true
+          selfHeal: true
+        syncOptions:
+        - ServerSideApply=true

argocd/applicationsets/kustomization.yaml

@@ -4,6 +4,7 @@ kind: Kustomization
 
 resources:
   - aitooling.yaml
+  - imageupdater.yaml
   - observability.yaml
   - platform.yaml
   - storage.yaml

argocd/applicationsets/platform.yaml

@@ -10,7 +10,7 @@ spec:
       repoURL: https://git.unkin.net/unkin/argocd-apps
       revision: HEAD
       directories:
-      - path: apps/overlays/*/artifactapi
+      - path: apps/overlays/*/argocd-image-updater
       - path: apps/overlays/*/cattle-system
       - path: apps/overlays/*/cert-manager
       - path: apps/overlays/*/certificates