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

includes/Admin/class-admin.php

@@ -69,10 +69,12 @@ class Admin {
         // Get the plugin version.
         $plugin_version = $this->core->get_plugin_version();
 
+        $plugin_url = $this->get_plugin_base_url();
+
         // Enqueue styles.
         \wp_enqueue_style(
             'wpst-admin-styles',
-            plugin_dir_url( dirname( __DIR__ ) ) . 'admin/css/admin-styles.css',
+            $plugin_url . 'admin/css/admin-styles.css',
             array(), // Dependencies.
             $plugin_version // Version.
         );
@@ -80,7 +82,7 @@ class Admin {
         // Enqueue admin scripts.
         \wp_enqueue_script(
             'wpst-admin-script',
-            plugin_dir_url( dirname( __DIR__ ) ) . 'admin/js/admin-scripts.js',
+            $plugin_url . 'admin/js/admin-scripts.js',
             array( 'jquery' ),
             $plugin_version, // Version.
             true
@@ -99,4 +101,21 @@ class Admin {
             $data
         );
     }
+
+    /**
+     * Get plugin base URL.
+     *
+     * @return string Plugin base URL with trailing slash.
+     */
+    private function get_plugin_base_url(): string {
+        if ( defined( 'WP_PLUGIN_STARTER_TEMPLATE_URL' ) ) {
+            return WP_PLUGIN_STARTER_TEMPLATE_URL;
+        }
+
+        if ( defined( 'WPST_PLUGIN_URL' ) ) {
+            return WPST_PLUGIN_URL;
+        }
+
+        return \plugin_dir_url( dirname( __DIR__, 2 ) );
+    }
 }