Rework saving to config

lib/mod_list.dart

@@ -13,7 +13,9 @@ class LoadOrder {
     return order.map((mod) => mod.id).toList();
   }
 
-  LoadOrder();
+  LoadOrder([List<Mod>? order]) {
+    this.order = order ?? [];
+  }
 
   bool get hasErrors => errors.isNotEmpty;
 }
@@ -204,6 +206,66 @@ class ModList {
     }
   }
 
+  void saveToConfig(LoadOrder loadOrder) {
+    final file = File(configPath);
+    final logger = Logger.instance;
+
+    try {
+      // Create XML builder
+      final builder = XmlBuilder();
+
+      // Add XML declaration
+      builder.declaration(encoding: 'utf-8');
+
+      // Add root element
+      builder.element(
+        'ModsConfigData',
+        nest: () {
+          // Add version element
+          builder.element('version', nest: '1.5.4297 rev994');
+
+          // Add active mods element
+          builder.element(
+            'activeMods',
+            nest: () {
+              // Add each mod as a list item
+              for (final mod in loadOrder.order) {
+                builder.element('li', nest: mod.id);
+                logger.info('Adding mod to config: ${mod.name} (${mod.id})');
+              }
+            },
+          );
+
+          // Add known expansions element
+          final expansions = mods.values.where((m) => m.isExpansion).toList();
+          if (expansions.isNotEmpty) {
+            builder.element(
+              'knownExpansions',
+              nest: () {
+                for (final mod in expansions) {
+                  builder.element('li', nest: mod.id);
+                  logger.info(
+                    'Adding expansion to config: ${mod.name} (${mod.id})',
+                  );
+                }
+              },
+            );
+          }
+        },
+      );
+
+      // Build the XML document
+      final xmlDocument = builder.buildDocument();
+
+      // Write the XML document to file
+      file.writeAsStringSync(xmlDocument.toString());
+      logger.info('Successfully saved mod configuration to: $configPath');
+    } catch (e) {
+      logger.error('Error saving configuration file: $e');
+      throw Exception('Failed to save config file: $e');
+    }
+  }
+
   void setEnabled(String modId, bool enabled) {
     if (mods.containsKey(modId)) {
       final mod = mods[modId]!;