chore: add changeset for clipboard copy interoperability

Author: Conobi

.changeset/clipboard-copy-interop.md

@@ -0,0 +1,13 @@
+---
+"note.box": minor
+---
+
+Add clipboard copy interoperability with external apps
+
+Copied content now pastes cleanly into Google Docs, Microsoft Word, Teams, Confluence, GitHub, and Telegram:
+- Tables copy with proper `<thead>`/`<tbody>` structure and inline border styles
+- Code blocks include `language-*` class for syntax highlighting in target apps
+- Task lists use standard HTML checkboxes
+- Plain text slot always contains Markdown
+
+New "Copy format" setting (Settings > Copy format) lets users choose between HTML (default, best for rich-text apps) and Markdown (best for GitHub, Telegram).