Issue-99: Prevent Alley Users from Appearing On the Site

[anubisthejackle]

Summary

This PR implements a new feature to prevent Alley users (and similar "staff" accounts) from appearing as public authors on the frontend of WordPress sites. It addresses #99.

Key aspects of the implementation include:

• Author archives for filtered accounts (e.g., those with Alley email domains) now return a 404.
• Author names and links are filtered in traditional authors, Byline Manager, and Co-Authors Plus integrations, replacing them with "Staff" as appropriate.
• The list of domains and environments affected by this feature can be customized via filters.
• Feature loading can be restricted by environment type, and this logic is now filterable for greater flexibility.
• Comprehensive automated tests have been added to ensure the feature works as expected and can be toggled by environment and product context.
• PHPUnit and test configuration updates were made to support new environment-based logic and exclude integration tests that require unavailable plugins by default.

Notes for reviewers

• The feature is modular and can be enabled/disabled or filtered by environment.
• Tests confirm correct behavior across different products and configurations.

Other Information

• I updated the README.md file for any new/updated features.
• I updated the CHANGELOG.md file for any new/updated features.

Changelog entries

Added

• New "Disable Alley Authors" feature to prevent staff user accounts from appearing as public authors.
• 404 responses for author archives of filtered accounts.
• Author name and link filtering for traditional authors, Byline Manager, and Co-Authors Plus.
• Customizable domain and environment filters for feature scope.
• Filter hooks to control feature loading by environment.
• PHPUnit config updates and new automated tests for this feature.

Changed

• Test configuration to support environment-based feature toggling.

Deprecated

Removed

Fixed

Security

[renatonascalves]

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