feat: unify execution and add workspace file imports

Remove Ask/Execute modes and general product tool approvals so requests use the selected runtime, enabled capabilities, and execution account permissions. Migrate retired application metadata while preserving user content.

Retire the Results page while retaining conversation images and stored artifacts. Add local and remote workspace file imports, timestamps and sorting, improve image discovery and saving, and refine workspace navigation and supervision responsiveness. Include the accompanying web-search changes, tests, probes, and product documentation.

Remote imports require an updated Agent. Existing artifacts are not automatically copied into project directories. Validation evidence and outstanding failures remain documented in feature progress files; no full test suite or real-model calls were rerun for this commit.

Release note: Run requests without switching work modes, import files into a selected local or remote workspace folder, sort workspace files by date, and keep using conversation images after removal of the Results page.

docs/features/task-and-job/task-center-prd.md

@@ -46,7 +46,6 @@ Job/Subjob/Run 树、独立详情或路由。
 - 名称和所属项目。
 - 关联 Conversation 标题。
 - Task 类型和触发来源。
-- Ask / Execute 模式。
 - 当前聚合状态。
 - 最近一次面向用户的进展。
 - 最近活动时间。
@@ -105,8 +104,8 @@ FR-TC3：任务累计执行时间按其历次执行请求汇总，周期触发
 ```text
 ▾ 产品发布讨论                           10:24
 
-   每周进度总结       每周 · Execute · 等待中 ●
-   发布前检查                     单次 · Execute ✓
+   每周进度总结       每周 · 等待中 ●
+   发布前检查                     单次 ✓
 ```
 
 - 无 Task 的 Conversation 保持现有单行样式。