Add cuisine subcategory filter, fix remap logic, and add OKE deployment manifests

- Add 파인다이닝/코스 cuisine type to 한식/일식/중식/양식 categories
- Change cuisine filter from flat list to grouped optgroup with subcategories
- Fix remap-foods/remap-cuisine: add jdbcType=CLOB, fix CLOB LISTAGG,
  improve retry logic (3 attempts, batch size 5), add error logging
- Add OKE deployment: Dockerfiles, K8s manifests, deploy.sh, deployment guide
- Add Next.js standalone output for Docker builds

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -10,3 +10,6 @@ node_modules/
 # Java backend
 backend-java/build/
 backend-java/.gradle/
+
+# K8s secrets (never commit)
+k8s/secrets.yaml