Diagram parameter need to be configurable

Diagram parameters are fixed atm. They should be configurable in the head section.

Look for diagram generation code in the repository, likely in a script or module. Identify where diagram parameters are currently hardcoded. The change involves making these parameters configurable via a head section, possibly in a configuration file or command-line arguments. Check for existing configuration parsing to understand the pattern to follow.

索引モデルが issue の本文から書いたものです。