fix(sync): 移除多线程下载并补齐staging复用回归

infrastructure/src/official_update.rs

@@ -96,8 +96,6 @@ pub struct OfficialUpdateConfig {
     pub audit_local: bool,
     /// Repair local files when the local manifest audit fails.
     pub repair: bool,
-    /// 下载并发度（并行执行的网络下载数）。默认 4，钳制到 `1..=256`。
-    pub download_concurrency: usize,
 }
 
 impl Default for OfficialUpdateConfig {
@@ -119,7 +117,6 @@ impl Default for OfficialUpdateConfig {
             force: false,
             audit_local: true,
             repair: true,
-            download_concurrency: crate::official_download::DEFAULT_DOWNLOAD_CONCURRENCY,
         }
     }
 }
@@ -901,8 +898,7 @@ impl OfficialUpdateService {
             &active_resource_root,
             &config.curl_command,
         )
-        .with_proxy_config(config.curl_proxy.clone())
-        .with_download_concurrency(config.download_concurrency);
+        .with_proxy_config(config.curl_proxy.clone());
         let snapshot_path = snapshot_path_for(config, &active_resource_root);
         let bootstrap_cache_path = config.bootstrap_cache_path();
 
@@ -1341,8 +1337,7 @@ impl OfficialUpdateService {
             &publish_plan.staging_path,
             &config.curl_command,
         )
-        .with_proxy_config(config.curl_proxy.clone())
-        .with_download_concurrency(config.download_concurrency);
+        .with_proxy_config(config.curl_proxy.clone());
         report.staging_path = Some(publish_plan.staging_path.clone());
         report.snapshot_path = staging_snapshot_path.clone();
         report.download_manifest = staging_fetcher.download_manifest_path();