完善分发与收集任务全流程

- RestJobEx 对齐 task_id，path_file 提交目录路径
- 运行页进度仅跟接口轮询，失败态停留 page3 UI
- 完成态卡位续做，USB/任务轮询生命周期优化
- 拆分 DLL 加载、任务 staging 与提交前校验
- 移除 mock 与冗余样式，补充 native 依赖

Co-authored-by: Cursor <cursoragent@cursor.com>

app/src/main/services/native-path.ts

@@ -88,5 +88,10 @@ export function setupNativeWorkingDir(): void {
   if (!process.env.PATH?.toLowerCase().includes(nativeDir.toLowerCase())) {
     process.env.PATH = `${pathHead}${path.delimiter}${process.env.PATH || ''}`
   }
-  log.debug(`Native DLL search path: ${nativeDir}; cwd kept at ${process.cwd()}`)
+  try {
+    process.chdir(execDir)
+  } catch (e) {
+    log.warn(`chdir to ${execDir} failed`, e)
+  }
+  log.debug(`Native DLL search path: ${nativeDir}; cwd=${process.cwd()}`)
 }