feat: add admin transaction create/update with auto payment status sync

Allow admins to edit transaction amount and status, recalculate payment totals, and mark invoices fully paid when paid transactions cover the payable amount.

components/payments/paymentValidator.js

@@ -1,6 +1,60 @@
-// Stub validator — pass-through middleware (no validation yet)
+// /components/payments/paymentValidator.js
+'use strict';
+
+const AppError = require('../../utils/AppError');
+
+const PAYMENT_METHODS = new Set(['online', 'card', 'cash']);
+const TRANSACTION_STATUSES = new Set(['pending', 'paid']);
+
 const passThrough = (req, res, next) => next();
 
-module.exports = new Proxy({}, {
-  get: () => passThrough
-});
+const validateTransactionBody = (body, { requireAmount = true } = {}) => {
+  const details = {};
+
+  if (requireAmount && (body.amount === undefined || body.amount === null || Number(body.amount) <= 0)) {
+    details.amount = 'مبلغ تراکنش باید بیشتر از صفر باشد';
+  } else if (body.amount !== undefined && Number(body.amount) < 0) {
+    details.amount = 'مبلغ تراکنش نمی‌تواند منفی باشد';
+  }
+
+  if (body.status !== undefined && !TRANSACTION_STATUSES.has(body.status)) {
+    details.status = 'وضعیت تراکنش نامعتبر است';
+  }
+
+  if (body.method !== undefined && body.method !== '' && !PAYMENT_METHODS.has(body.method)) {
+    details.method = 'روش پرداخت نامعتبر است';
+  }
+
+  if (body.notes !== undefined && String(body.notes).length > 5000) {
+    details.notes = 'یادداشت نباید بیش از ۵۰۰۰ کاراکتر باشد';
+  }
+
+  if (Object.keys(details).length) {
+    throw new AppError('VALIDATION_FAILED', details);
+  }
+};
+
+const validateAddTransaction = (req, res, next) => {
+  try {
+    validateTransactionBody(req.body || {}, { requireAmount: true });
+    next();
+  } catch (err) {
+    next(err);
+  }
+};
+
+const validateUpdateTransaction = (req, res, next) => {
+  try {
+    validateTransactionBody(req.body || {}, { requireAmount: false });
+    next();
+  } catch (err) {
+    next(err);
+  }
+};
+
+module.exports = {
+  validateCreatePayment: passThrough,
+  validateUpdatePayment: passThrough,
+  validateAddTransaction,
+  validateUpdateTransaction
+};