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/messages/[instanceId]/chats.get.ts

@@ -0,0 +1,47 @@
+/**
+ * GET /api/messages/:instanceId/chats
+ * Get all chats for an instance
+ */
+import { query } from '../../../utils/database'
+
+interface ChatRow {
+  id: string
+  jid: string
+  name: string | null
+  is_group: boolean
+  unread_count: number
+  last_message_at: Date | null
+}
+
+export default defineEventHandler(async (event) => {
+  const username = getHeader(event, 'x-authentik-username')
+  if (!username) {
+    throw createError({ statusCode: 401, message: 'Unauthorized' })
+  }
+
+  const instanceId = getRouterParam(event, 'instanceId')
+
+  // Verify instance exists
+  const instanceCheck = await query('SELECT id FROM instances WHERE id = $1', [instanceId])
+  if (instanceCheck.rows.length === 0) {
+    throw createError({ statusCode: 404, message: 'Instance not found' })
+  }
+
+  // Get chats with last message
+  const result = await query<ChatRow>(
+    `SELECT c.id, c.jid, c.name, c.is_group, c.unread_count, c.last_message_at
+     FROM chats c
+     WHERE c.instance_id = $1
+     ORDER BY c.last_message_at DESC NULLS LAST`,
+    [instanceId]
+  )
+
+  return result.rows.map(row => ({
+    id: row.id,
+    jid: row.jid,
+    name: row.name || row.jid.split('@')[0],
+    isGroup: row.is_group,
+    unreadCount: row.unread_count,
+    lastMessageAt: row.last_message_at
+  }))
+})