Add professor share calculation and financial reporting feature

Introduces per-class payout configuration (percentage or hourly rate,
plus an optional per-session expense allowance), pure calculation
utilities for professor payout/net profit/receivables, and a new
financial-reports API surface with per-class, per-session, and
date-range/monthly reports. Also adds full CRUD for institutional
expenses used in the range report, and wires up the new permissions
and roles. Fixes a pre-existing ReferenceError (missing
parseImportDate import) in paymentService that blocked creating
payments with dated transactions.

components/expenses/expenseValidator.js

@@ -0,0 +1,50 @@
+// /components/expenses/expenseValidator.js
+'use strict';
+
+const AppError = require('../../utils/AppError');
+
+const validateBody = (body, { isUpdate = false } = {}) => {
+  const details = {};
+
+  if (!isUpdate || body.title !== undefined) {
+    if (!body.title || !String(body.title).trim()) {
+      details.title = 'عنوان هزینه الزامی است';
+    }
+  }
+
+  if (!isUpdate || body.amount !== undefined) {
+    if (body.amount === undefined || body.amount === null || Number(body.amount) <= 0) {
+      details.amount = 'مبلغ هزینه باید بیشتر از صفر باشد';
+    }
+  }
+
+  if (!isUpdate || body.date !== undefined) {
+    if (!body.date || Number.isNaN(new Date(body.date).getTime())) {
+      details.date = 'تاریخ هزینه الزامی و باید معتبر باشد';
+    }
+  }
+
+  if (Object.keys(details).length) {
+    throw new AppError('VALIDATION_FAILED', details);
+  }
+};
+
+const validateCreateExpense = (req, res, next) => {
+  try {
+    validateBody(req.body, { isUpdate: false });
+    next();
+  } catch (err) {
+    next(err);
+  }
+};
+
+const validateUpdateExpense = (req, res, next) => {
+  try {
+    validateBody(req.body, { isUpdate: true });
+    next();
+  } catch (err) {
+    next(err);
+  }
+};
+
+module.exports = { validateCreateExpense, validateUpdateExpense };