pubish 2025 dec 2

Fix inconsistent code-cell language specifications (#756)

* misc

* Fix inconsistent code-cell language specifications in optimal savings lectures

Standardize code-cell language specifications to eliminate jupytext UserWarnings:
- os_egm_jax.md: Change ipython to python3 (no IPython magics used)
- os_stochastic.md: Change ipython to python3 (no IPython magics used)
- os_time_iter.md: Change all cells to ipython (uses !pip install magic)

These changes ensure consistent language specifications within each notebook,
resolving warnings during jupytext conversion while maintaining functionality.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

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Co-authored-by: Claude <noreply@anthropic.com>