C2(deploy-infra-alerting): impl use custom payload for ntfy-native JSON

Replace Grafana's default webhook JSON with ntfy-native JSON via
payloadTemplate. The template produces:
  {"topic":"infra-alerts","title":"[FIRING] ...","message":"...","actions":[...]}

This gives clean notifications instead of raw Grafana JSON blobs.
Uses coll.Dict/data.ToJSON template functions (Grafana 12+).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

argocd/manifests/grafana/alerting.yaml

@@ -7,13 +7,11 @@ contactPoints:
       - uid: ntfy-infra-webhook
         type: webhook
         settings:
-          url: https://ntfy.ops.eblu.me/infra-alerts
+          url: https://ntfy.ops.eblu.me
           httpMethod: POST
-          title: >-
-            {{ template "ntfy-infra.title" . }}
-          message: >-
-            {{ template "ntfy-infra.message" . }}
           maxAlerts: "0"
+          payloadTemplate: >-
+            {{ template "ntfy-infra.payload" . }}
         disableResolveMessage: false
 
 policies:
@@ -89,13 +87,16 @@ templates:
   - orgId: 1
     name: ntfy-infra
     template: |
-      {{ define "ntfy-infra.title" -}}
-      [{{ .Status | toUpper }}] {{ .CommonLabels.alertname }}
-      {{- end }}
-
-      {{ define "ntfy-infra.message" -}}
+      {{ define "ntfy-infra.payload" -}}
+      {{ $msg := "" -}}
       {{ range .Alerts -}}
-      {{ .Annotations.summary }}
-      {{ if .Annotations.runbook_url }}Runbook: {{ .Annotations.runbook_url }}{{ end }}
+      {{ $msg = printf "%s%s\n" $msg .Annotations.summary -}}
       {{ end -}}
-      {{- end }}
+      {{ $actions := coll.Slice -}}
+      {{ range .Alerts -}}
+      {{ if .Annotations.runbook_url -}}
+      {{ $actions = coll.Slice (coll.Dict "action" "view" "label" "Open Runbook" "url" .Annotations.runbook_url "clear" false) -}}
+      {{ end -}}
+      {{ end -}}
+      {{ data.ToJSON (coll.Dict "topic" "infra-alerts" "title" (printf "[%s] %s" (.Status | toUpper) .CommonLabels.alertname) "message" $msg "priority" 3 "actions" $actions) -}}
+      {{ end }}