Do not load admin code on frontend (#41)

In #40 an undefined variable warning was noticed. There is no need to load `PluginInstall` and `ThemeInstall` classes on frontend. The `Helper` trait was left in place as in a future it could contain helpful code for other classes.

* Do not load admin code when on frontend

* Fix workflows

---------

Co-authored-by: xxsimoxx <simone@gieffeedizioni.it>

Author: xxsimoxx

.github/workflows/cpcs.yml

@@ -21,7 +21,7 @@ jobs:
             sed -i '/MY_DOMAIN/ s//classicpress-directory-integration/' phpcs.xml
             mv phpcs.xml phpcs.xml.dist
         - name: CPCS checks
-          uses: 10up/wpcs-action@stable
+          uses: 10up/wpcs-action@v1.7.0
           with:
             use_local_config: 'true'
             enable_warnings: 'true'

.github/workflows/wpcs.yml

@@ -13,7 +13,7 @@ jobs:
       steps:
         - uses: actions/checkout@v4
         - name: WPCS checks
-          uses: 10up/wpcs-action@stable
+          uses: 10up/wpcs-action@v1.7.0
           with:
             use_local_config: 'true'
             enable_warnings: 'true'

classicpress-directory-integration.php

@@ -61,18 +61,10 @@ function error_is_wp() {
 require_once 'classes/class-plugin-update.php';
 $plugin_update = new PluginUpdate();
 
-// Load Plugin Install functionality class.
-require_once 'classes/class-plugin-install.php';
-$plugin_install = new PluginInstall();
-
 // Load Theme Update functionality class.
 require_once 'classes/class-theme-update.php';
 $theme_update = new ThemeUpdate();
 
-// Load Theme Install functionality class.
-require_once 'classes/class-theme-install.php';
-$theme_install = new ThemeInstall();
-
 // Register text domain
 function register_text_domain() {
 	load_plugin_textdomain( 'classicpress-directory-integration', false, dirname( plugin_basename( __FILE__ ) ) . '/languages' );
@@ -84,3 +76,15 @@ function register_text_domain() {
 if ( defined( 'WP_CLI' ) && WP_CLI ) {
 	\WP_CLI::add_command( 'cpdi', '\ClassicPress\Directory\CPDICLI' );
 }
+
+if ( ! is_admin() ) {
+	return;
+}
+
+// Load Plugin Install functionality class.
+require_once 'classes/class-plugin-install.php';
+$plugin_install = new PluginInstall();
+
+// Load Theme Install functionality class.
+require_once 'classes/class-theme-install.php';
+$theme_install = new ThemeInstall();