Added a "unsaved changed" warning dialog for part, entity edits and system settings

This fixes issue #1368

assets/tomselect/form_reset_handler/form_reset_handler.js

@@ -0,0 +1,46 @@
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2026 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * TomSelect plugin for dirty-check integration and form reset support.
+ *
+ * Sets data-default-value on the underlying <select> so the dirty-check
+ * controller can detect changes, and restores that value when the form is reset.
+ */
+export default function form_reset_handler() {
+    const self = this;
+    const input = this.input;
+
+    // Multiple selects not yet supported
+    if (input.multiple) {
+        return;
+    }
+
+    // Always capture the initial value, even empty string.
+    // Empty string is falsy, so the old `|| null` guard would silently skip it,
+    // leaving data-default-value unset and breaking the dirty check for blank defaults.
+    input.dataset.defaultValue = input.value;
+
+    if (input.form) {
+        input.form.addEventListener('reset', () => {
+            input.value = input.dataset.defaultValue ?? '';
+            self.sync();
+        });
+    }
+}