Feature/global exclusion list

[gin0115]

Changes proposed in this Pull Request

This pull request introduces a new multi-layer link exclusion system for the Internet Archive Wayback Machine Link Fixer plugin, allowing links to be excluded from checking and archiving based on a built-in list, user settings, or a per-link flag. It includes updates to backend logic, admin UI, E2E and unit tests, and developer tooling for comprehensive testing and management of exclusion rules.

Core exclusion logic and settings:

• Refactored Link_Exclusion to support three exclusion layers: built-in patterns (now bundled in Settings::BUNDLED_LINK_EXCLUSIONS and filterable), user settings, and per-link flags. Added methods to check each layer and updated filtering logic to use the new structure. [1] [2]
• Added Settings::BUNDLED_LINK_EXCLUSIONS constant and get_bundled_link_exclusions() method to provide a filterable built-in exclusion list, defaulting to LinkedIn domains. [1] [2]

Integration with link checking and admin UI:

• Updated Link_Check_Action::check_link() to skip checking links matched by any exclusion layer, treating them as valid and un-checked. [1] [2]
• Enhanced the link details admin panel to display clear messages and disable the exclusion checkbox if a link is excluded by user settings or the built-in list, following the correct priority order. [1] [2]

Testing and developer tooling:

• Added a comprehensive E2E test (link-details-exclusion.spec.js) and a helper mu-plugin (iawmlf-e2e-exclusion.php) to seed, toggle, and clean up test links, verifying the correct exclusion priority and UI behavior. [1] [2] [3]
• Introduced a new PHPUnit test (Test_Link_Check_Action) to ensure the backend skips excluded links and checks non-excluded links as expected.

Testing instructions

Mentions #