feat(dashboard): selector de empresa + flag p_all en _dash_responses

app/dashboard/page.tsx

@@ -14,6 +14,14 @@ import { FilterSidebar }         from '@/components/dashboard/filter-sidebar'
 import type { DashboardFilters } from '@/lib/dashboard-types'
 
 // El survey_id se pasa como query param: /dashboard?survey_id=UUID
+// '00000000-0000-0000-0000-000000000000' = flag p_all (vista agregada de todos los surveys)
+const SURVEY_OPTIONS = [
+  { label: 'Todos', id: '00000000-0000-0000-0000-000000000000' },
+  { label: 'InQuality', id: '30000000-0000-0000-0000-000000000002' },
+  { label: 'Fundación Solidaridad', id: '30000000-0000-0000-0000-000000000003' },
+  { label: 'Demo', id: '30000000-0000-0000-0000-000000000001' },
+]
+
 export default function DashboardPage() {
   const searchParams = useSearchParams()
   const surveyId = searchParams.get('survey_id') ?? '30000000-0000-0000-0000-000000000001'
@@ -40,6 +48,22 @@ export default function DashboardPage() {
             Datos agregados · k-anonimato k≥5 · Encuesta Mapeo de Cuidadores 2026
             {filters.depto && <span className="db-active-filter"> · Filtro: {filters.depto}</span>}
           </p>
+          <nav className="db-survey-nav" aria-label="Selección de empresa">
+            {SURVEY_OPTIONS.map((opt) => (
+              <a
+                key={opt.id}
+                href={`/dashboard?survey_id=${opt.id}`}
+                className={
+                  opt.id === surveyId
+                    ? 'db-survey-link db-survey-link-active'
+                    : 'db-survey-link'
+                }
+                aria-current={opt.id === surveyId ? 'page' : undefined}
+              >
+                {opt.label}
+              </a>
+            ))}
+          </nav>
         </header>
 
         {/* Fila 1: KPIs (span 12) */}