feat: 新增 MinIO 对象存储与算力节点缓存预下载

- 后端新增 storage 模块（minio_store），支持 MinIO 预签名 URL 上传与对象管理
- config 新增 MinIO 及存储等待相关配置项
- 算力节点新增 /compute/cache/prepare 缓存预下载接口（带校验和原子落盘）
- 算力节点健康接口增加存储可用性探针
- SQL 迁移补充资源存储相关表结构
- Docker 新增 minio 服务与后端 minio 配置
- 补充 minio-compute-cache-plan 设计文档

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

docker/minio/docker-compose.yml

@@ -0,0 +1,19 @@
+services:
+  minio:
+    image: minio/minio:RELEASE.2025-02-28T09-55-16Z
+    container_name: yg-ft-minio
+    command: server /data --console-address ":9001"
+    environment:
+      MINIO_ROOT_USER: ${MINIO_ACCESS_KEY:-minioadmin}
+      MINIO_ROOT_PASSWORD: ${MINIO_SECRET_KEY:-change_me_minio_secret}
+    ports:
+      - "${MINIO_API_PORT:-9000}:9000"
+      - "${MINIO_CONSOLE_PORT:-9001}:9001"
+    volumes:
+      - ${MINIO_DATA_ROOT_HOST:-./data}:/data
+    healthcheck:
+      test: ["CMD-SHELL", "curl -fsS http://127.0.0.1:9000/minio/health/live || exit 1"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+    restart: unless-stopped