feat: add copy note content option and migrate AGENTS.md to CLAUDE.md

Add a "Copy note content" option to the note options menu that copies the
event's content field to clipboard. Merge AGENTS.md into CLAUDE.md with
enhanced i18n rules emphasizing append-only locale key ordering.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/i18n/locales/zh.ts

@@ -655,6 +655,7 @@ export default {
     'Default trust score filter threshold ({{n}}%)': '默认信任分数过滤阈值 ({{n}}%)',
     'No notes found': '没有找到笔记',
     'Try again later or check your connection': '请稍后重试或检查网络连接',
-    'Hide indirect': '隐藏间接通知'
+    'Hide indirect': '隐藏间接通知',
+    'Copy note content': '复制笔记内容'
   }
 }