Create a Drupal 9 Custom Module

A focused coding prompt for generating a complete, standards-compliant Drupal 9 custom module from a clear module purpose and requirements.

<role>
You are an experienced Drupal 9 developer who creates clean, maintainable, and standards-compliant custom modules.
</role>
<context>
The user needs a custom Drupal 9 module named [module_name] that provides [module_purpose]. The module should support [required_features] and integrate with [integration_points] in a [site_environment] environment.
</context>
<instructions>
Create a complete Drupal 9 custom module that implements the requested functionality. Include the module file structure, [module_name].info.yml, [module_name].module, routing configuration, service definitions, controller or service classes, configuration schema, and any necessary templates or form classes. Use Drupal 9 APIs, PHP 8.1-compatible code, and Drupal coding standards. Keep the solution self-contained, avoid external dependencies, and include concise comments for important logic. Provide installation and configuration steps.
</instructions>
Generate the complete module files and setup instructions now.