docs: organize product design by feature

Define repository and feature-scoped documentation rules for PRDs, User Stories, logic, UI, technical design, and progress evidence.

Move feature-owned documents under docs/features, add one entry point per feature, remove the redundant docs index, and update all affected cross-references. Expand the local tool environment design with explicit product, story, logic, UI, technical, and progress documents.

docs/features/computer-control/README.md

@@ -0,0 +1,11 @@
+# 电脑控制
+
+电脑控制包含 GoodBuddy 对浏览器和客户端桌面能力的产品实现与平台适配状态。
+
+## 文档导航
+
+| 文档 | 权威职责 |
+| --- | --- |
+| [功能进度](./progress.md) | 当前已实现能力、缺陷修复、平台限制和验证状态 |
+
+当前只有进度文档；产品需求、功能逻辑、UI 和技术设计尚未从历史实现记录中独立整理。