feat: open local runtime clients from the composer

Add composer shortcuts for local Continue and OpenCode terminals and the official DeepSeek Harness Web client, using the current project and model bridge. Manage browser service reuse, stop actions and terminal cleanup. Upgrade DeepSeek Harness to 0.1.7-rc.2 and Cordis to 4.0.4.

Include the coordinated IPC handler extraction and related tests and documentation. Remote native-client coordinator wiring, managed Node consolidation, Ask MCP mappings and full desktop/package acceptance remain unfinished; this commit records the implemented local workflow and supporting SSH groundwork.

Validation: typecheck and lint passed; 267 focused tests passed and 5 skipped. No new real-provider calls were made for this commit. Prior real-model evidence and remaining acceptance work are documented in the feature progress files.

Release note: 本地项目选择 Continue 或 OpenCode 后，可从输入框下方打开原生终端；选择 DS 后，可打开使用当前项目和模型的官方 Web 客户端。客户端使用独立会话，DS 网页关闭后服务继续运行，可在 GoodBuddy 中停止；远程入口尚未完成。

docs/features/deepseek-harness/README.md

@@ -16,3 +16,12 @@
 [Runtime 进程复用技术设计](../assistant-workbar/runtime-process-reuse-technical-design.md)
 统一维护；本 Runtime 的生命周期见[技术设计 §9](./technical-design.md#9-runtime-生命周期)，
 未发布实现的验收状态见[工作栏进度](../assistant-workbar/progress.md#2026-09-14-runtime-进程复用实施中)。
+
+The separate official Web client is pinned to `@deepseek-ai/dsh@0.1.7-rc.2`.
+Its Main service API, Ask/Execute policy, capability adapters, packaged resource
+layout, and Windows validation are documented in
+[Native Client Proposal, section 9.1](../assistant-workbar/runtime-native-client-proposal.md#91-ds-web-backend-2026-09-26).
+This Web resource tree is prepared separately from the background Harness Host.
+Current shortcut/coordinator behavior and configured-model evidence are tracked in
+[local native client progress](../assistant-workbar/progress.md#2026-09-27-local-native-client-validation),
+including the remaining managed Node delivery gap.