This PR implements several code quality improvements to meet PHPStan level 2 requirements. The changes fix issues with property access, type declarations, and namespace resolutions across classes.

Changes

• Set PHPStan analysis level to 2
• Fixed property access of an object of \WP_Site
  • Changed incorrect name property to correct blogname property
• Addressed property naming of object of type \WP_Network
  • Renamed sitename to site_name for consistency
  • Ignoring false positive when access to private $blog_id property through magic methods
• Fixed parameter type declaration of var that is passed to WP_MS_Networks_List_Table::pagination()
• Ignoring root namespace resolution issue for WP_User return type from WP_CLI\Fetchers\User::get()

No functional changes have been made — these are strictly quality improvements that help prevent potential bugs and make the codebase easier to maintain.