```

feat(api): 添加 MinIO 文件下载支持并优化流处理

添加了对 MinIO 存储文件的直接下载支持，包括：
- 新增 urlparse 和 Config 导入用于 URL 解析和配置读取
- 集成 s3_client 扩展用于 MinIO 对象存储操作
- 实现同源文件检测逻辑，判断是否为 MinIO 存储的文件
- 添加 MinIO 文件流式下载功能，支持大文件处理
- 优化流处理过程中的资源管理，确保请求和文件对象正确关闭
- 增强安全性，验证同源策略防止任意 URL 访问
```

blueprints/api.py

@@ -1,5 +1,7 @@
 from flask import Blueprint, request, jsonify, session, current_app
-from extensions import db, redis_client
+from urllib.parse import unquote, urlparse
+from config import Config
+from extensions import db, redis_client, s3_client
 from models import User, SavedPrompt
 from middlewares.auth import login_required
 from services.logger import system_logger
@@ -244,12 +246,39 @@ def download_proxy():
         return jsonify({"error": "缺少 URL 参数"}), 400
 
     try:
+        parsed_url = urlparse(url)
+        public_prefix = Config.MINIO["public_url"].rstrip("/") + "/"
+        is_same_origin_file = (
+            parsed_url.path.startswith(public_prefix)
+            and (not parsed_url.scheme or parsed_url.netloc == request.host)
+        )
+        if is_same_origin_file:
+            object_key = unquote(parsed_url.path[len(public_prefix):])
+            file_obj = s3_client.get_object(Bucket=Config.MINIO["bucket"], Key=object_key)
+            headers = {
+                "Content-Type": file_obj.get("ContentType") or "application/octet-stream",
+                "Content-Disposition": f'attachment; filename="{filename}"',
+                "Cache-Control": "private, max-age=0",
+            }
+
+            def generate_minio_stream():
+                try:
+                    for chunk in file_obj["Body"].iter_chunks(chunk_size=4096):
+                        yield chunk
+                finally:
+                    file_obj["Body"].close()
+
+            return current_app.response_class(generate_minio_stream(), headers=headers)
+
         req, headers = get_remote_file_stream(url)
         headers["Content-Disposition"] = f'attachment; filename="{filename}"'
 
         def generate_stream():
+            try:
                 for chunk in req.iter_content(chunk_size=4096):
                     yield chunk
+            finally:
+                req.close()
 
         return current_app.response_class(generate_stream(), headers=headers)
     except Exception as e: