feat(financial-reports): add charts, trends and forecasts overview tab

Adds a new "نمای کلی و نمودارها" tab to the financial reports page with
KPI cards, daily/weekly income-trend and monthly breakdown charts, a
payment-status doughnut, a due-date cash-flow forecast chart, and full
per-class income and upcoming-payments tables — backed by chart.js /
vue-chartjs and the new /financial-reports/admin/analytics endpoint.

src/api/financialReportApi.js

@@ -4,5 +4,6 @@ import axiosInstance from './axiosInstance';
 export const financialReportApi = {
   getClassReport: (classId) => axiosInstance.get(`/financial-reports/admin/classes/${classId}`),
   getSessionReport: (sessionId) => axiosInstance.get(`/financial-reports/admin/sessions/${sessionId}`),
-  getRangeReport: (params) => axiosInstance.get('/financial-reports/admin/range', { params })
+  getRangeReport: (params) => axiosInstance.get('/financial-reports/admin/range', { params }),
+  getAnalytics: (params) => axiosInstance.get('/financial-reports/admin/analytics', { params })
 };