feat(sat): agrega ProxyManager para rotación de proxies

- Nuevo servicio apps/api/src/services/sat/proxy.service.ts.
- Soporta estrategias round-robin y random.
- Parsea SAT_PROXY_LIST y crea agentes HttpsProxyAgent.
- Script scripts/test-proxy-rotation.ts para validar configuración.

apps/api/scripts/test-proxy-rotation.ts

@@ -0,0 +1,20 @@
+import 'dotenv/config';
+import { ProxyManager } from '../src/services/sat/proxy.service.js';
+
+const manager = new ProxyManager(
+  process.env.SAT_PROXY_LIST || '',
+  (process.env.SAT_PROXY_STRATEGY as any) || 'round-robin',
+);
+
+console.log(`Total de proxies: ${manager.getProxyCount()}`);
+console.log(`Estrategia: ${process.env.SAT_PROXY_STRATEGY || 'round-robin'}`);
+console.log('Próximos 10 proxies seleccionados:');
+
+for (let i = 0; i < 10; i++) {
+  const proxy = manager.getNextProxy();
+  if (!proxy) {
+    console.log(`  ${i + 1}. (sin proxy configurado)`);
+  } else {
+    console.log(`  ${i + 1}. ${proxy.host}:${proxy.port}`);
+  }
+}