Add Flux CD GitOps sync for alaska/core stacks

Prepares clusters/production/ for `flux bootstrap git` - Kustomizations
for manifests/alaska and manifests/core, plus a Gitea push Receiver so
new commits reconcile immediately instead of waiting on the poll
interval. Webhook exposed on a dedicated host (flux-webhook.workolik.com)
to avoid the existing queue.workolik.com Gateway/Ingress overlap.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

manifests/alaska/kustomization.yaml

@@ -0,0 +1,6 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - alaska.yaml
+  - k8s-dashboard.yaml