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/neft_transaction.dart

@@ -0,0 +1,31 @@
+class NeftTransaction {
+  final String fromAccount;
+  final String toAccount;
+  final String amount;
+  final String ifscCode;
+  final String remitterName;
+  final String beneficiaryName;
+  final String tpin;
+
+  NeftTransaction({
+    required this.fromAccount,
+    required this.toAccount,
+    required this.amount,
+    required this.ifscCode,
+    required this.remitterName,
+    required this.beneficiaryName,
+    required this.tpin,
+  });
+
+  Map<String, dynamic> toJson() {
+    return {
+      'fromAccount': fromAccount,
+      'toAccount': toAccount,
+      'amount': amount,
+      'ifscCode': ifscCode,
+      'remitterName': remitterName,
+      'beneficiaryName': beneficiaryName,
+      'tpin': tpin,
+    };
+  }
+}