feat: Implement major features and fix theming bug

This commit introduces several new features and a critical bug fix.

- Implemented a full "Quick Pay" flow for both within and outside the bank, including IFSC validation, beneficiary verification, and a TPIN-based payment process.
- Added a date range filter to the Account Statement screen and streamlined the UI by removing the amount filters.
- Fixed a major bug that prevented dynamic theme changes from being applied. The app now correctly switches between color themes.
- Refactored and improved beneficiary management, transaction models, and the fund transfer flow to support NEFT/RTGS.

lib/api/services/neft_service.dart

@@ -0,0 +1,30 @@
+import 'package:dio/dio.dart';
+import 'package:kmobile/data/models/neft_response.dart';
+import 'package:kmobile/data/models/neft_transaction.dart';
+
+class NeftService {
+  final Dio _dio;
+
+  NeftService(this._dio);
+
+  Future<NeftResponse> processNeftTransaction(NeftTransaction transaction) async {
+    try {
+      await Future.delayed(const Duration(seconds: 3));
+      final response = await _dio.post(
+        '/api/payment/neft',
+        data: transaction.toJson(),
+      );
+
+      if (response.statusCode == 200) {
+        return NeftResponse.fromJson(response.data);
+      } else {
+        throw Exception(
+            'NEFT transaction failed with status code: ${response.statusCode}');
+      }
+    } on DioException catch (e) {
+      throw Exception('Failed to process NEFT transaction: ${e.message}');
+    } catch (e) {
+      throw Exception('An unexpected error occurred: ${e.toString()}');
+    }
+  }
+}