feat: v3.1.0 OSS直连优化与代码质量提升

- 🚀 OSS 直连上传下载（用户直连OSS，不经过后端）
- ✨ 新增 Presigned URL 签名接口
- ✨ 支持自定义 OSS endpoint 配置
- 🐛 修复 buildS3Config 不支持自定义 endpoint 的问题
- 🐛 清理残留的 basic-ftp 依赖
- ♻️ 更新 package.json 项目描述和版本号
- 📝 完善 README.md 更新日志和 CORS 配置说明
- 🔒 安全性增强：签名 URL 15分钟/1小时有效期

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

backend/package.json

@@ -1,22 +1,24 @@
 {
-  "name": "ftp-web-manager-backend",
-  "version": "1.0.0",
-  "description": "FTP Web Manager Backend",
+  "name": "wanwanyun-backend",
+  "version": "3.1.0",
+  "description": "玩玩云 - 云存储管理平台后端服务",
   "main": "server.js",
   "scripts": {
     "start": "node server.js",
     "dev": "nodemon server.js"
   },
   "keywords": [
-    "ftp",
-    "web",
-    "file-manager"
+    "cloud-storage",
+    "oss",
+    "s3",
+    "file-manager",
+    "alibaba-cloud",
+    "tencent-cloud"
   ],
-  "author": "",
+  "author": "玩玩云团队",
   "license": "MIT",
   "dependencies": {
     "archiver": "^7.0.1",
-    "basic-ftp": "^5.0.4",
     "bcryptjs": "^3.0.3",
     "better-sqlite3": "^11.8.1",
     "cookie-parser": "^1.4.7",
@@ -28,7 +30,8 @@
     "jsonwebtoken": "^9.0.2",
     "multer": "^2.0.2",
     "nodemailer": "^6.9.14",
-    "ssh2-sftp-client": "^12.0.1",
+    "@aws-sdk/client-s3": "^3.600.0",
+    "@aws-sdk/lib-storage": "^3.600.0",
     "svg-captcha": "^1.4.0"
   },
   "devDependencies": {