Remove redundant py_to_notebook tool in favor of Jupytext

- Delete bin/py_to_notebook.py and tito/tools/py_to_notebook.py
- Update notebooks command to use Jupytext directly
- Jupytext is already configured in all *_dev.py files
- Simpler, more standard workflow using established tools
- Better integration with NBDev ecosystem

Benefits:
- Eliminates duplicate conversion tools
- Uses industry-standard Jupytext instead of custom tool
- Reduces maintenance burden
- Better error handling and compatibility

bin/py_to_notebook.py

@@ -1,122 +0,0 @@
-#!/usr/bin/env python3
-"""
-Convert Python files with cell markers to Jupyter notebooks.
-
-Usage:
-    python3 bin/py_to_notebook.py modules/tensor/tensor_dev.py
-    python3 bin/py_to_notebook.py modules/tensor/tensor_dev.py --output custom_name.ipynb
-"""
-
-import argparse
-import json
-import re
-import sys
-from pathlib import Path
-
-def convert_py_to_notebook(py_file: Path, output_file: Path = None):
-    """Convert Python file with cell markers to notebook."""
-    
-    if not py_file.exists():
-        print(f"❌ File not found: {py_file}")
-        return False
-    
-    # Read the Python file
-    with open(py_file, 'r') as f:
-        content = f.read()
-    
-    # Split into cells based on # %% markers
-    cells = re.split(r'^# %%.*$', content, flags=re.MULTILINE)
-    cells = [cell.strip() for cell in cells if cell.strip()]
-    
-    # Create notebook structure
-    notebook = {
-        'cells': [],
-        'metadata': {
-            'kernelspec': {
-                'display_name': 'Python 3',
-                'language': 'python',
-                'name': 'python3'
-            },
-            'language_info': {
-                'name': 'python',
-                'version': '3.8.0'
-            }
-        },
-        'nbformat': 4,
-        'nbformat_minor': 4
-    }
-    
-    for i, cell_content in enumerate(cells):
-        if not cell_content:
-            continue
-            
-        # Check if this is a markdown cell
-        if cell_content.startswith('# ') and '\n' in cell_content:
-            lines = cell_content.split('\n')
-            if lines[0].startswith('# ') and not any(line.strip() and not line.startswith('#') for line in lines[:5]):
-                # This looks like a markdown cell
-                cell = {
-                    'cell_type': 'markdown',
-                    'metadata': {},
-                    'source': []
-                }
-                
-                for line in lines:
-                    if line.startswith('# '):
-                        cell['source'].append(line[2:] + '\n')
-                    elif line.startswith('#'):
-                        cell['source'].append(line[1:] + '\n')
-                    elif line.strip() == '':
-                        cell['source'].append('\n')
-                
-                notebook['cells'].append(cell)
-                continue
-        
-        # Code cell
-        cell = {
-            'cell_type': 'code',
-            'execution_count': None,
-            'metadata': {},
-            'outputs': [],
-            'source': []
-        }
-        
-        for line in cell_content.split('\n'):
-            cell['source'].append(line + '\n')
-        
-        # Remove trailing newline from last line
-        if cell['source'] and cell['source'][-1].endswith('\n'):
-            cell['source'][-1] = cell['source'][-1][:-1]
-        
-        notebook['cells'].append(cell)
-    
-    # Determine output file
-    if output_file is None:
-        output_file = py_file.with_suffix('.ipynb')
-    
-    # Write notebook
-    output_file.parent.mkdir(parents=True, exist_ok=True)
-    with open(output_file, 'w') as f:
-        json.dump(notebook, f, indent=2)
-    
-    print(f"✅ Converted {py_file} → {output_file}")
-    return True
-
-def main():
-    parser = argparse.ArgumentParser(description="Convert Python files to Jupyter notebooks")
-    parser.add_argument('input_file', type=Path, help='Input Python file')
-    parser.add_argument('--output', '-o', type=Path, help='Output notebook file')
-    parser.add_argument('--verbose', '-v', action='store_true', help='Verbose output')
-    
-    args = parser.parse_args()
-    
-    success = convert_py_to_notebook(args.input_file, args.output)
-    
-    if not success:
-        sys.exit(1)
-    
-    if args.verbose:
-        print("🎉 Conversion complete!")
-
-if __name__ == "__main__":
-    main()