Move py_to_notebook.py to bin/ directory for better organization

- Moved tools/py_to_notebook.py to bin/py_to_notebook.py
- Updated tito.py to reference the new location
- Made py_to_notebook.py executable for direct invocation
- Removed empty tools/ directory
- Updated documentation to reflect new location
- All tools now consolidated in bin/ directory for consistency

Benefits:
- Conventional organization (bin/ for executables)
- Can invoke tools directly: ./bin/py_to_notebook.py
- Cleaner project structure
- Consistent with other tools (tito.py, generate_student_notebooks.py)

bin/py_to_notebook.py

@@ -0,0 +1,122 @@
+#!/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() 

bin/tito.py

@@ -824,7 +824,7 @@ def cmd_notebooks(args):
         try:
             # Use the separate py_to_notebook.py tool
             result = subprocess.run([
-                sys.executable, "tools/py_to_notebook.py", str(dev_file)
+                sys.executable, "bin/py_to_notebook.py", str(dev_file)
             ], capture_output=True, text=True)
             
             module_name = dev_file.parent.name