chore: improve workflow names and fix CSS indentation consistency (#18)

* fix: resolve plugin class loading reliability issues

* fix: address CodeRabbit XSS and accessibility findings from PR #18

- admin/js/admin-scripts.js: replace HTML string interpolation in showNotice
  with DOM API construction and .text() to prevent XSS; whitelist type values
- admin/js/update-source-selector.js: replace .html(message) with .text(message)
  in showMessage to prevent XSS from AJAX response content
- admin/templates/modal.php: add role=dialog, aria-modal=true, aria-labelledby
  for screen reader semantics; replace <span> close control with <button> for
  keyboard operability and proper ARIA role

tests/phpunit/bootstrap.php

@@ -46,7 +46,7 @@ if ( getenv( 'WP_PHPUNIT__DIR' ) ) {
     // Include plugin files needed for tests.
     require_once WPST_PLUGIN_DIR . 'includes/class-core.php';
     require_once WPST_PLUGIN_DIR . 'includes/class-plugin.php';
-    if ( file_exists( WPST_PLUGIN_DIR . 'admin/lib/admin.php' ) ) {
-        require_once WPST_PLUGIN_DIR . 'admin/lib/admin.php';
+    if ( file_exists( WPST_PLUGIN_DIR . 'includes/Admin/class-admin.php' ) ) {
+        require_once WPST_PLUGIN_DIR . 'includes/Admin/class-admin.php';
     }
 }