Auto-create notebooks y sesiones en jupyter_exec (append y cell).
Auto-create en jupyter_write (append_code, append_markdown, batch).
Nuevos subcomandos cleanup y shutdown-all en jupyter_kernel.
README.md renombrado a README.txt para evitar error de parseo del indexer.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>