What-if savings planner page (wishlist #7)

New Planificador page: the current savings pace (prefilled from the
live budget projection's monthly net, editable) versus a scenario with
extra monthly savings, both compounded at a configurable annual rate
over a 1-40 year horizon — side-by-side totals and growth curves.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/Layout.tsx

@@ -2,6 +2,7 @@ import { useState, useEffect } from "react";
 import { Link, Outlet, useLocation, useNavigate } from "react-router-dom";
 import {
   Sparkles,
+  Telescope,
   Calculator,
   BarChart3,
   Landmark,
@@ -55,6 +56,7 @@ const navSections: NavSection[] = [
       { to: "/salarios", icon: Landmark, label: "Salarios" },
       { to: "/pensions", icon: PiggyBank, label: "Pensiones" },
       { to: "/proyecciones", icon: TrendingUp, label: "Proyecciones" },
+      { to: "/planificador", icon: Telescope, label: "Planificador" },
       { to: "/analytics", icon: BarChart3, label: "Analytics" },
     ],
   },