ci: add Hugo blog CI/CD to k3s

- Enable Gitea Container Registry
- Dockerfile: nginx:alpine serving hugo public/
- Gitea Actions: build & push image + deploy to k3s
- k8s manifests: namespace hugo, deployment, service, ingress
- RBAC: allow runner to update deployments in hugo ns
- .gitignore: add public/ (CI builds it)

deploy/hugo-ingress.yaml

@@ -0,0 +1,24 @@
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: hugo-blog
+  namespace: hugo
+  annotations:
+    cert-manager.io/cluster-issuer: letsencrypt-prod
+spec:
+  ingressClassName: traefik
+  rules:
+  - host: hugo.test.luochen570.cn
+    http:
+      paths:
+      - path: /
+        pathType: Prefix
+        backend:
+          service:
+            name: hugo-blog
+            port:
+              number: 80
+  tls:
+  - hosts:
+    - hugo.test.luochen570.cn
+    secretName: hugo-test-luochen570-cn-tls