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/ko.ts

@@ -672,6 +672,7 @@ export default {
     'Default trust score filter threshold ({{n}}%)': '기본 신뢰 점수 필터 임계값 ({{n}}%)',
     'No notes found': '노트를 찾을 수 없습니다',
     'Try again later or check your connection': '나중에 다시 시도하거나 연결을 확인하세요',
-    'Hide indirect': '간접 숨기기'
+    'Hide indirect': '간접 숨기기',
+    'Copy note content': '노트 내용 복사'
   }
 }