docs(claude): restructure documentation management and add feedback system

- Restructure §8 from "文档沉淀规则" to "文档管理规则" with 4 subsections
  - Add docs/ structure with features/ and knowledge-base/ directories
  - Add feature documentation template with 7 sections (概述/设计初衷/技术设计/预期作用/实际效果/演化路线/头脑风暴)
  - Add feature update trigger matrix (新增/修改/完成/问题/反馈)
  - Add documentation quality checklist
- Add §16

desktop/src/components/Feedback/index.ts

@@ -0,0 +1,11 @@
+export { FeedbackButton } from './FeedbackButton';
+export { FeedbackModal } from './FeedbackModal';
+export { FeedbackHistory } from './FeedbackHistory';
+export {
+  useFeedbackStore,
+  type FeedbackSubmission,
+  type FeedbackType,
+  type FeedbackPriority,
+  type FeedbackStatus,
+  type FeedbackAttachment,
+} from './feedbackStore';