Add DEPOSITO transaction type and Salarios page

New TransactionType.DEPOSITO for salary deposits from n8n/Gmail flow.
New /salarios endpoint with summary. New top-level Salarios page with
DataTable and summary cards. Push notifications link to /salarios for
deposits.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/Layout.tsx

@@ -3,6 +3,7 @@ import {
   LayoutDashboard,
   Calculator,
   BarChart3,
+  Landmark,
   LogOut,
   Wallet,
   Menu,
@@ -27,6 +28,7 @@ import { cn } from '@/lib/utils';
 const navItems = [
   { to: '/', icon: LayoutDashboard, label: 'Dashboard' },
   { to: '/budget', icon: Calculator, label: 'Presupuesto' },
+  { to: '/salarios', icon: Landmark, label: 'Salarios' },
   { to: '/analytics', icon: BarChart3, label: 'Analytics' },
 ];