Add nav config module, budget-cycle helper, me/recent API helpers

navigation.ts becomes the single source of truth for sidebar and
breadcrumbs (Inicio entry added; '/' is exact-match).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -130,6 +130,8 @@ export async function logout() {
   await fetch("/api/auth/logout", { method: "POST", credentials: "same-origin" });
 }
 
+export const getMe = () => api.get<{ username: string }>("/auth/me");
+
 // ─── Types ──────────────────────────────────────────────────────────────────
 
 export type Account = Schema<'AccountRead'>;
@@ -240,6 +242,11 @@ export const upsertBalanceOverride = (
 export const deleteBalanceOverride = (year: number, month: number) =>
   api.delete(`/budget/balance-override/${year}/${month}`);
 
+// --- Transactions ---
+
+export const getRecentTransactions = (limit = 5) =>
+  api.get<Transaction[]>("/transactions/recent", { params: { limit } });
+
 // --- Installment Plans (Tasa Cero) ---
 
 export type InstallmentPlan = Schema<'InstallmentPlanRead'>;

frontend/src/lib/dates.ts

@@ -18,6 +18,29 @@ export function formatShortDate(dateStr: string): string {
   });
 }
 
+/** Budget month M = the credit-card cycle ENDING on the 18th of M
+ * (matches get_cycle_range in the backend). After the 18th we are already
+ * in next month's cycle — including the Dec 19 → January-next-year wrap. */
+export function currentBudgetCycle(today = new Date()): {
+  year: number;
+  month: number;
+  start: Date;
+  end: Date;
+} {
+  let year = today.getFullYear();
+  let month = today.getMonth() + 1;
+  if (today.getDate() > 18) {
+    month += 1;
+    if (month === 13) {
+      month = 1;
+      year += 1;
+    }
+  }
+  const end = new Date(year, month - 1, 18);
+  const start = new Date(year, month - 2, 18);
+  return { year, month, start, end };
+}
+
 /** "hace 3 días" / "hace 2 horas" / "hace un momento" */
 export function formatRelativeAge(iso: string): string {
   const ms = Date.now() - new Date(iso).getTime();

frontend/src/lib/navigation.ts

@@ -0,0 +1,71 @@
+import {
+  BarChart3,
+  Calculator,
+  Droplets,
+  Home,
+  Landmark,
+  Layers,
+  PiggyBank,
+  RefreshCw,
+  Sparkles,
+  Telescope,
+  TrendingUp,
+  type LucideIcon,
+} from "lucide-react";
+
+/** Single source of truth for the sidebar nav and header breadcrumbs. */
+
+export interface NavItem {
+  to: string;
+  icon: LucideIcon;
+  label: string;
+}
+
+export interface NavSection {
+  label: string;
+  items: NavItem[];
+}
+
+export const navSections: NavSection[] = [
+  {
+    label: "General",
+    items: [
+      { to: "/", icon: Home, label: "Inicio" },
+      { to: "/asistente", icon: Sparkles, label: "Asistente" },
+      { to: "/sync", icon: RefreshCw, label: "Sincronización" },
+    ],
+  },
+  {
+    label: "Finanzas",
+    items: [
+      { to: "/budget", icon: Calculator, label: "Presupuesto" },
+      { to: "/salarios", icon: Landmark, label: "Salarios" },
+      { to: "/financiamientos", icon: Layers, label: "Financiamientos" },
+      { to: "/pensions", icon: PiggyBank, label: "Pensiones" },
+      { to: "/proyecciones", icon: TrendingUp, label: "Proyecciones" },
+      { to: "/planificador", icon: Telescope, label: "Planificador" },
+      { to: "/analytics", icon: BarChart3, label: "Analytics" },
+    ],
+  },
+  {
+    label: "Servicios",
+    items: [
+      { to: "/servicios-municipales", icon: Droplets, label: "Municipalidad" },
+    ],
+  },
+];
+
+/** "/" must match exactly — prefix-matching it would mark Inicio active everywhere. */
+export function isNavActive(to: string, pathname: string): boolean {
+  if (to === "/") return pathname === "/";
+  return pathname === to || pathname.startsWith(`${to}/`);
+}
+
+export function titleFor(pathname: string): string {
+  for (const section of navSections) {
+    for (const item of section.items) {
+      if (isNavActive(item.to, pathname)) return item.label;
+    }
+  }
+  return "WealthySmart";
+}