feat: complete fases 3,4,5 - frontend, containers, e2e tests

FASE 3 - Frontend (22 paginas):
- Leads (listado, detalle, nuevo), Cotizaciones, Arqueo
- Cursos, Alumnos, Empresas (listado, detalle, ventas)
- Reportes (ventas, ventas-empresas, reimpresion)
- Autorizador, Contacto

FASE 4 - Contenedores:
- docker-compose.yml (backend-api + services-externos + frontend)
- Dockerfiles para backend, services-externos, frontend
- .env.example con secretos

FASE 5 - Pruebas E2E:
- Playwright config + 3 spec files (login, leads, dashboard)
- 7 escenarios: login, error, sidebar, crear lead,
  dashboard cards, timeout, reportes

tests/e2e/dashboard.spec.ts

@@ -0,0 +1,29 @@
+import { test, expect } from '@playwright/test';
+
+test('dashboard carga cards de resumen', async ({ page }) => {
+  await page.goto('/login');
+  await page.fill('[name="rut"]', '12345678-5');
+  await page.fill('[name="clave"]', 'password');
+  await page.click('button:has-text("Ingresar")');
+  await expect(page.locator('.card')).toHaveCount(4);
+});
+
+test('timeout de inactividad redirige a login', async ({ page }) => {
+  await page.goto('/login');
+  await page.fill('[name="rut"]', '12345678-5');
+  await page.fill('[name="clave"]', 'password');
+  await page.click('button:has-text("Ingresar")');
+  await page.clock.install();
+  await page.clock.fastForward(1800001);
+  await expect(page).toHaveURL(/\/login/);
+});
+
+test('reportes ventas carga datos', async ({ page }) => {
+  await page.goto('/login');
+  await page.fill('[name="rut"]', '12345678-5');
+  await page.fill('[name="clave"]', 'password');
+  await page.click('button:has-text("Ingresar")');
+  await page.goto('/reportes/ventas');
+  await page.click('button:has-text("Generar")');
+  await expect(page.locator('table')).toBeVisible();
+});