Fix list_files

I am not sure why, but list-files isn't working. My next step would be to add some debugging. This example may help:
```
import logging
from quart import Quart, jsonify

# Configure logging settings
logging.basicConfig(filename='app.log', level=logging.DEBUG, format='%(asctime)s - %(levelname)s - %(message)s')

app = Quart(__name__)

@app.route('/')
async def index():
# Add an info log message
logging.info('Index route was accessed')
return jsonify({'message': 'Hello, World!'})

@app.route('/error')
async def error():
try:
# Simulate an error
result = 1 / 0
except Exception as e:
# Add an error log message with exception details
logging.error(f'An error occurred: {e}')
return jsonify({'error': 'An error occurred'}), 500

return jsonify({'result': result})

if __name__ == '__main__':
app.run(debug=True, host='0.0.0.0', port=5003)
```

The issue identifies the list-files operation but no implementation file or test. Start by locating the list-files entry point and reproducing the failure with logging enabled, using the Quart example as a reference. Done means the operation works and a regression check confirms the expected file listing.

索引モデルが issue の本文から書いたものです。