Add module deletion support on uninstall and update documentation

[roble]

This pull request introduces a new uninstall behavior for the Saucebase module installer, making module directory deletion on composer remove opt-in rather than the default. It also updates the documentation to clarify configuration options, core behaviors, and frontend framework support. Comprehensive tests are added for the new behavior.

Uninstall behavior changes:

• By default, uninstalling a module via composer remove now skips deleting the module directory. To enable deletion, set module-delete-on-remove: true in the root composer.json extra section. [1] [2]
• The uninstall logic continues to protect path repository modules from deletion, regardless of the delete flag.
• Added PHPUnit tests to verify the new uninstall guard, the configuration flag, and path repository precedence. [1] [2]

Documentation and configuration updates:

• Expanded the README.md and added CLAUDE.md to document all configuration keys, default values, and behaviors, including uninstall, update strategies, excluded directories, and frontend framework support. [1] [2] [3] [4] [5] [6]
• Clarified how to override defaults and provided practical examples for all configuration options. [1] [2] [3]

Frontend framework support:

• Documented how the installer copies only the files for the active frontend framework (Vue, React, Svelte) based on frontend.json, and how unused framework files are handled. [1] [2]

These changes improve safety during module removal, clarify configuration for users, and ensure the installer’s behaviors are well-documented and thoroughly tested.