v0.11.4 Improved error reporting / Added nbexec flags

v0.11.4, 2026/06/07 Improved error reporting / Added nbexec flags

• nbexec: Added -export_html flag to export the executed notebook to HTML at a specified target path.
• nbexec: Added -check_cells flag to check and report cells that failed execution, exiting with code 1 if any failure occurs.
• Fixed an issue where the Cell/Line or errors were not being displayed correctly.
• Extended cell compilation error hover popups to also trigger when hovering over the cell/line area, in addition to the file/line area.
• Added support for rich HTML execution/runtime error reporting, enabling hoverable popups that show code context directly over Go stack traces printed to stderr (e.g. panics and fatal logs).
• Refactored execution error handling: stderr streams in real-time to Jupyter (not buffered), and the rich hover-popup HTML boxes for cell-related error lines are printed after the execution exits.
• Improved error CSS layout to wrap long code lines without displaying horizontal scrollbars.