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-and-job-model.md

@@ -233,7 +233,7 @@ waiting_approval > failed > running > paused > idle
 - Task 只能关联同一 Project 范围内允许使用的 Conversation。
 - Renderer 不能把任意 Task 或 Job 绑定到其他 Project 的 Conversation。
 - Job/Subjob 继承 Task 的能力上限，只能缩小，不能扩大。
-- Execute Task 冻结 Runtime、工作目录、工具和审批策略；后台触发不能扩大权限。
+- Task 请求冻结 Runtime、工作目录和能力范围；后台触发不增加未启用能力，不保存模式或一般审批策略。
 - 并行输出先有界持久化，再按确定顺序汇总到 Conversation。
 - 取消、超时、审批和应用退出必须沿 Task → Job / Subjob → Run → Runtime 传播。
 - 删除 Task 默认保留 Conversation 和消息；删除 Conversation 必须处理其全部关联 Task。