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/components/NoteOptions/useMenuActions.tsx

@@ -187,6 +187,14 @@ export function useMenuActions({
           closeDrawer()
         }
       },
+      {
+        icon: Copy,
+        label: t('Copy note content'),
+        onClick: () => {
+          navigator.clipboard.writeText(event.content)
+          closeDrawer()
+        }
+      },
       {
         icon: Code,
         label: t('View raw event'),