feat: WhatsApp Nucleo con Nuxt 4 + Baileys v7

Reemplazo completo de Evolution API por implementación directa con Baileys.

Características:
- Dashboard completo con Nuxt UI v4
- Soporte para múltiples instancias de WhatsApp
- Conexión via QR code o pairing code
- Persistencia de mensajes en PostgreSQL
- API REST para integraciones externas
- Webhooks con firma HMAC
- SSE para actualizaciones en tiempo real
- Autenticación con Authentik

server/api/instances/index.post.ts

@@ -0,0 +1,48 @@
+/**
+ * POST /api/instances
+ * Create a new instance
+ */
+import { query } from '../../utils/database'
+
+interface CreateInstanceBody {
+  name: string
+}
+
+interface InstanceRow {
+  id: string
+  name: string
+  phone_number: string | null
+  status: string
+  created_at: Date
+}
+
+export default defineEventHandler(async (event) => {
+  // Check auth
+  const username = getHeader(event, 'x-authentik-username')
+  if (!username) {
+    throw createError({ statusCode: 401, message: 'Unauthorized' })
+  }
+
+  const body = await readBody<CreateInstanceBody>(event)
+
+  if (!body.name?.trim()) {
+    throw createError({ statusCode: 400, message: 'Name is required' })
+  }
+
+  const result = await query<InstanceRow>(
+    `INSERT INTO instances (name, created_by)
+     VALUES ($1, $2)
+     RETURNING id, name, phone_number, status, created_at`,
+    [body.name.trim(), username]
+  )
+
+  const instance = result.rows[0]
+
+  return {
+    id: instance.id,
+    name: instance.name,
+    phoneNumber: instance.phone_number,
+    status: instance.status,
+    createdAt: instance.created_at
+  }
+})