feat: Kaniko 기반 CI/CD 설정

- gitea-runner: DinD 제거, Host 모드 전환
- gitea-runner: ServiceAccount, RBAC 추가
- gitea ns: zot-registry-credentials ExternalSecret 추가
- argocd ns: zot-registry-credentials ExternalSecret 추가

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

gitea-runner/manifests/zot-secret.yaml

@@ -0,0 +1,27 @@
+apiVersion: external-secrets.io/v1
+kind: ExternalSecret
+metadata:
+  name: zot-registry-credentials
+  namespace: gitea
+spec:
+  refreshInterval: 1h
+  secretStoreRef:
+    kind: ClusterSecretStore
+    name: vault-backend
+  target:
+    name: zot-registry-credentials
+    creationPolicy: Owner
+    template:
+      type: kubernetes.io/dockerconfigjson
+      data:
+        .dockerconfigjson: |
+          {"auths":{"zot0213.kro.kr":{"username":"{{ .USERNAME }}","password":"{{ .PASSWORD }}","auth":"{{ printf "%s:%s" .USERNAME .PASSWORD | b64enc }}"}}}
+  data:
+    - secretKey: USERNAME
+      remoteRef:
+        key: zot
+        property: USERNAME
+    - secretKey: PASSWORD
+      remoteRef:
+        key: zot
+        property: PASSWORD