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/FeedbackButton.tsx

@@ -0,0 +1,40 @@
+import { MessageCircle } from 'lucide-react';
+import { motion } from 'framer-motion';
+import { useFeedbackStore } from './feedbackStore';
+import { Button } from '../ui';
+
+interface FeedbackButtonProps {
+  onClick: () => void;
+  showCount?: boolean;
+}
+
+export function FeedbackButton({ onClick, showCount = true }: FeedbackButtonProps) {
+  const feedbackItems = useFeedbackStore((state) => state.feedbackItems);
+  const pendingCount = feedbackItems.filter((f) => f.status === 'pending' || f.status === 'submitted').length;
+
+  return (
+    <motion.div
+      whileHover={{ scale: 1.02 }}
+      whileTap={{ scale: 0.98 }}
+    >
+      <Button
+        variant="ghost"
+        size="sm"
+        onClick={onClick}
+        className="relative flex items-center gap-2 text-gray-600 dark:text-gray-300 hover:text-gray-900 dark:hover:text-gray-100"
+      >
+        <MessageCircle className="w-4 h-4" />
+        <span className="text-sm">Feedback</span>
+        {showCount && pendingCount > 0 && (
+          <motion.span
+            initial={{ scale: 0 }}
+            animate={{ scale: 1 }}
+            className="absolute -top-1 -right-1 w-4 h-4 bg-orange-500 text-white text-[10px] rounded-full flex items-center justify-center"
+          >
+            {pendingCount > 9 ? '9+' : pendingCount}
+          </motion.span>
+        )}
+      </Button>
+    </motion.div>
+  );
+}