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/data/models/beneficiary.dart

@@ -1,5 +1,3 @@
-
-
 // ignore_for_file: non_constant_identifier_names
 
 class Beneficiary {
@@ -9,6 +7,7 @@ class Beneficiary {
   final String ifscCode;
   final String? bankName;
   final String? branchName;
+  final String? tpin;
 
   Beneficiary({
     required this.accountNo,
@@ -17,30 +16,43 @@ class Beneficiary {
     required this.ifscCode,
     this.bankName,
     this.branchName,
+    this.tpin,
   });
 
   factory Beneficiary.fromJson(Map<String, dynamic> json) {
     return Beneficiary(
-      accountNo: json['accountNo'] ?? '',
-      accountType: json['accountType'] ?? '',
+      accountNo: json['account_no'] ?? json['accountNo'] ?? '',
+      accountType: json['account_type'] ?? json['accountType'] ?? '',
       name: json['name'] ?? '',
-      ifscCode: json['ifscCode'] ?? '',
-      bankName: json['bankName'] ?? '',
-      branchName: json['branchName'] ?? '',
+      ifscCode: json['ifsc_code'] ?? json['ifscCode'] ?? '',
+      bankName: json['bank_name'] ?? json['bankName'] ?? '',
+      branchName: json['branch_name'] ?? json['branchName'] ?? '',
     );
   }
-      
+
   Map<String, dynamic> toJson() {
-    return {
+    final Map<String, dynamic> json = {
       'accountNo': accountNo,
       'accountType': accountType,
       'name': name,
-      'ifscCode' : ifscCode,
+      'ifscCode': ifscCode,
     };
+    if (bankName != null && bankName!.isNotEmpty) {
+      json['bankName'] = bankName;
+    }
+    if (branchName != null && branchName!.isNotEmpty) {
+      json['branchName'] = branchName;
+    }
+    if (tpin != null && tpin!.isNotEmpty) {
+      json['tpin'] = tpin;
+    }
+    return json;
   }
 
   static List<Beneficiary> listFromJson(List<dynamic> jsonList) {
-    final beneficiaryList = jsonList.map((beneficiary) => Beneficiary.fromJson(beneficiary)).toList();
+    final beneficiaryList = jsonList
+        .map((beneficiary) => Beneficiary.fromJson(beneficiary))
+        .toList();
     print(beneficiaryList);
     return beneficiaryList;
   }
@@ -49,4 +61,5 @@ class Beneficiary {
   String toString() {
     return 'Beneficiary(accountNo: $accountNo, accountType: $accountType, ifscCode: $ifscCode, name: $name)';
   }
-}
+}
+