feat(dashboard): add pending/upcoming expenses table

- Backend: GET /expenses/pending-upcoming returns PENDING expenses with dueDate <= today+5 days, classified as overdue/upcoming
- DashboardExpensesTable: groups by periodicExpenseId, shows summed totals with status badges, links to /expenses?periodicExpenseId=X
- Expenses route accepts ?periodicExpenseId search param and pre-selects it in the filter
- fix: BeloAnalysisPage DatePicker type mismatch

apps/frontend/src/routes/_authenticated/expenses.tsx

@@ -1,6 +1,10 @@
 import { createFileRoute } from "@tanstack/react-router";
+import { z } from "zod";
 import { ExpensesPage } from "@/features/expenses/ExpensesPage";
 
 export const Route = createFileRoute("/_authenticated/expenses")({
+  validateSearch: z.object({
+    periodicExpenseId: z.coerce.number().optional(),
+  }),
   component: ExpensesPage,
 });