Error executing python notebook with multiple code cells

### Describe the bug

Error executing python notebook with multiple code cells. it expects all code cells merged into one python file.

### Affected version

_No response_

### Steps to reproduce the behavior

Ask GitHub copilot cli to execute a .ipynb file that has multiple code cells.

### Expected behavior

It should be able execute one code cell at a time sequentially.

### Additional context

_No response_

Start by reproducing the issue with GitHub Copilot CLI and a Python .ipynb file containing multiple code cells. Trace how the CLI loads and executes notebook cells, then verify that cells run sequentially rather than being merged into one Python file.

由索引模型根据 Issue 内容生成。