feat(expenses): add import functionality for expenses and total pending calculation

apps/backend/src/modules/expenses/handlers/getTotalPending.ts

@@ -0,0 +1,7 @@
+import type { Context } from "hono";
+import { getTotalPending } from "../expenses.service";
+
+export async function getTotalPendingHandler(c: Context) {
+  const result = await getTotalPending();
+  return c.json(result);
+}