feat: add copy page button functionality and fix llms-text output (#5419)

* feat: add copy page button functionality and fix llms-text output

- Add copy page button with CSS and JS implementation
- Implement copy page hooks for MkDocs integration
- Fix HTML filtering and DOM text reinterpreted as HTML issues
- Update llms-text target to generate docs/llm.txt instead of docs/llms-full.txt
- Add necessary styling and package.json dependencies

* fix missing button in preview

* remove the over-processing

* disable API reference

docs/mkdocs.yml

@@ -362,6 +362,7 @@ markdown_extensions:
   - github-callouts
 hooks:
   - _scripts/notebook_hooks.py
+  - _scripts/copy_page_hooks.py
 extra:
   social:
     - icon: fontawesome/brands/js