added chat app

Chat-App/lib/services/deepl_service.dart

@@ -0,0 +1,50 @@
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+
+class DeepLService {
+  Future<String?> translateText({
+    required String apiKey,
+    required String text,
+    required String targetLang,
+    String sourceLang = 'AUTO',
+    bool useFreeApi = true,
+  }) async {
+    if (apiKey.isEmpty || text.trim().isEmpty) return null;
+
+    final base = useFreeApi ? 'https://api-free.deepl.com' : 'https://api.deepl.com';
+    final uri = Uri.parse('$base/v2/translate');
+
+    try {
+      final response = await http.post(
+        uri,
+        headers: {
+          'Authorization': 'DeepL-Auth-Key $apiKey',
+          'Content-Type': 'application/x-www-form-urlencoded',
+        },
+        body: {
+          'text': text,
+          'target_lang': targetLang,
+          if (sourceLang.isNotEmpty && sourceLang.toUpperCase() != 'AUTO')
+            'source_lang': sourceLang,
+          'preserve_formatting': '1',
+        },
+      );
+
+      if (response.statusCode == 200) {
+        final jsonBody = json.decode(utf8.decode(response.bodyBytes));
+        final translations = jsonBody['translations'] as List<dynamic>?;
+        if (translations != null && translations.isNotEmpty) {
+          return translations.first['text']?.toString();
+        }
+        return null;
+      } else {
+        // Swallow errors and return null to avoid blocking the main save flow
+        return null;
+      }
+    } catch (_) {
+      return null;
+    }
+  }
+}
+
+