v0.1.8

• Never cache backend and login requests (/wp-admin/, wp-login.php, wp-register.php, AJAX) to prevent admin/login-side script issues.
• Clear all cache layers automatically after WordPress core, plugin, and theme updates.
• Keep redirect responses out of page cache to avoid stale/blank cached pages.
• Bump plugin version metadata to 0.1.8.
• Add/update test coverage for login request non-cacheability and update-triggered cache purge behavior.