fix: use actual R2 file size instead of client-side size

functions/upload/index.js

@@ -227,12 +227,16 @@ async function uploadFileToCloudflareR2(context, fullId, metadata, returnLink) {
 
     const R2DataBase = env.img_r2;
 
-    // 写入R2数据库
-    await R2DataBase.put(fullId, formdata.get('file'));
+    // 写入R2数据库，获取实际存储大小
+    const r2Object = await R2DataBase.put(fullId, formdata.get('file'));
 
     // 更新metadata
     metadata.Channel = "CloudflareR2";
     metadata.ChannelName = r2Channel.name || "R2_env";
+    // 使用 R2 返回的实际文件大小
+    if (r2Object && r2Object.size) {
+        metadata.FileSize = (r2Object.size / 1024 / 1024).toFixed(2);
+    }
 
     // 图像审查，采用R2的publicUrl
     const R2PublicUrl = r2Channel.publicUrl;