fix: 修复文件预览重定向与扩展名解析

server/media/s3/s3.go

@@ -248,16 +248,14 @@ func (ah *awshandler) Headers(tenantID types.TenantID, method string, url *url.U
 	}
 
 	if redirURL != "" {
-		// Return presigned URL with 308 Permanent redirect. Let the client cache the response.
-		// The original URL will stop working after a short period of time to prevent use of Tinode
-		// as a free file server.
+		// Return a temporary redirect to a short-lived presigned URL.
 		return http.Header{
 				"Location":      {redirURL},
 				"ETag":          {`"` + fdef.ETag + `"`},
 				"Content-Type":  {"application/json; charset=utf-8"},
 				"Cache-Control": {ah.conf.CacheControl},
 			},
-			http.StatusPermanentRedirect, nil
+			http.StatusFound, nil
 	}
 	return nil, 0, nil
 }