Fix InvoiceShelf install/update package manager execution.

Use Corepack-managed Yarn when available so installs respect upstream packageManager metadata and avoid Yarn classic mismatch failures during both fresh installs and updates.

CHANGELOG.md

@@ -487,7 +487,8 @@ Exercise vigilance regarding copycat or coat-tailing sites that seek to exploit
 
 ### 🆕 New Scripts
 
-  - Kiwix ([#15131](https://github.com/community-scripts/ProxmoxVE/pull/15131))
+  - Feishin ([#15130](https://github.com/community-scripts/ProxmoxVE/pull/15130))
+- Kiwix ([#15131](https://github.com/community-scripts/ProxmoxVE/pull/15131))
 - Add runtime status guard and deleted script stubs [@michelroegl-brunner](https://github.com/michelroegl-brunner) ([#15125](https://github.com/community-scripts/ProxmoxVE/pull/15125))
 
 ## 2026-06-15

ct/invoiceshelf.sh

@@ -52,8 +52,14 @@ function update_script() {
     msg_info "Updating Application"
     cd /opt/invoiceshelf
     $STD composer install --no-dev --optimize-autoloader
-    $STD yarn install
-    $STD yarn build
+    if command -v corepack >/dev/null 2>&1; then
+      $STD corepack enable
+      $STD corepack yarn install
+      $STD corepack yarn build
+    else
+      $STD yarn install
+      $STD yarn build
+    fi
     $STD php artisan migrate --force
     $STD php artisan optimize:clear
     chown -R www-data:www-data /opt/invoiceshelf

install/invoiceshelf-install.sh

@@ -39,8 +39,14 @@ sed -i "s|^DB_USERNAME=.*|DB_USERNAME=${PG_DB_USER}|" .env
 sed -i "s|^DB_PASSWORD=.*|DB_PASSWORD=${PG_DB_PASS}|" .env
 COMPOSER_ALLOW_SUPERUSER=1 $STD composer install --no-dev --optimize-autoloader --no-interaction
 $STD php artisan key:generate
-$STD yarn install
-$STD yarn build
+if command -v corepack >/dev/null 2>&1; then
+  $STD corepack enable
+  $STD corepack yarn install
+  $STD corepack yarn build
+else
+  $STD yarn install
+  $STD yarn build
+fi
 mkdir -p storage/framework/{cache,sessions,views} storage/logs bootstrap/cache
 chown -R www-data:www-data /opt/invoiceshelf
 chmod -R 775 storage bootstrap/cache