feat: historial de cambios (usuario, fecha, detalle)

Tabla change_history, pantalla en Agencia OS y registro automático
al guardar o enriquecer Zona de marca.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/DashboardShell.tsx

@@ -24,6 +24,7 @@ import {
   BookMarked,
   Sparkles,
   Images,
+  History,
 } from 'lucide-react';
 import TenantSwitcher from '@/components/TenantSwitcher';
 import type { DashboardModuleId } from '@/lib/tenant-modules';
@@ -282,7 +283,7 @@ export default function DashboardShell({
             <span className="px-3 text-[10px] font-bold uppercase tracking-wider text-gray-500">
               Agencia OS
             </span>
-            <div className="mt-1">
+            <div className="mt-1 space-y-0.5">
               <NavLink
                 item={{
                   href: '/dashboard/agencia',
@@ -292,6 +293,15 @@ export default function DashboardShell({
                 }}
                 onNavigate={close}
               />
+              <NavLink
+                item={{
+                  href: '/dashboard/historial',
+                  label: 'Historial de cambios',
+                  icon: History,
+                  iconClass: 'text-slate-500',
+                }}
+                onNavigate={close}
+              />
             </div>
           </div>
         ) : null}