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}`);
+  }
+}

apps/api/src/services/sat/proxy.service.ts

@@ -0,0 +1,100 @@
+import { HttpsProxyAgent } from 'https-proxy-agent';
+
+export interface ProxyConfig {
+  url: string;
+  host: string;
+  port: number;
+  username?: string;
+  password?: string;
+}
+
+export type ProxyStrategy = 'round-robin' | 'random';
+
+function parseProxyList(raw: string): ProxyConfig[] {
+  if (!raw.trim()) return [];
+
+  const configs: ProxyConfig[] = [];
+  const items = raw.split(',').map(s => s.trim()).filter(Boolean);
+
+  for (const item of items) {
+    try {
+      const url = new URL(item);
+      if (url.protocol !== 'http:' && url.protocol !== 'https:') {
+        console.warn(`[ProxyManager] Protocolo no soportado, se omite: ${item}`);
+        continue;
+      }
+      configs.push({
+        url: item,
+        host: url.hostname,
+        port: Number(url.port) || (url.protocol === 'https:' ? 443 : 80),
+        username: url.username || undefined,
+        password: url.password || undefined,
+      });
+    } catch (err) {
+      console.warn(`[ProxyManager] URL de proxy inválida, se omite: ${item}`);
+    }
+  }
+
+  return configs;
+}
+
+export class ProxyManager {
+  private proxies: ProxyConfig[];
+  private strategy: ProxyStrategy;
+  private currentIndex = 0;
+
+  constructor(
+    proxyList = process.env.SAT_PROXY_LIST || '',
+    strategy: ProxyStrategy = (process.env.SAT_PROXY_STRATEGY as ProxyStrategy) || 'round-robin',
+  ) {
+    this.proxies = parseProxyList(proxyList);
+    this.strategy = ['round-robin', 'random'].includes(strategy) ? strategy : 'round-robin';
+
+    if (this.proxies.length > 0) {
+      console.log(`[ProxyManager] ${this.proxies.length} proxy(s) configurados (estrategia: ${this.strategy})`);
+    } else {
+      console.log('[ProxyManager] No hay proxies configurados; se usará la IP directa del servidor');
+    }
+  }
+
+  hasProxies(): boolean {
+    return this.proxies.length > 0;
+  }
+
+  getProxyCount(): number {
+    return this.proxies.length;
+  }
+
+  getNextProxy(): ProxyConfig | null {
+    if (this.proxies.length === 0) return null;
+
+    if (this.strategy === 'random') {
+      return this.proxies[Math.floor(Math.random() * this.proxies.length)];
+    }
+
+    const proxy = this.proxies[this.currentIndex];
+    this.currentIndex = (this.currentIndex + 1) % this.proxies.length;
+    return proxy;
+  }
+
+  createAgent(proxy: ProxyConfig): HttpsProxyAgent<string> {
+    return new HttpsProxyAgent(proxy.url);
+  }
+
+  /**
+   * Crea un agente con el siguiente proxy del pool.
+   * Útil cuando se quiere una nueva conexión por solicitud.
+   */
+  createNextAgent(): HttpsProxyAgent<string> | null {
+    const proxy = this.getNextProxy();
+    if (!proxy) return null;
+    console.log(`[ProxyManager] Usando proxy: ${proxy.host}:${proxy.port}`);
+    return this.createAgent(proxy);
+  }
+}
+
+/**
+ * Instancia global del proxy manager.
+ * Lee SAT_PROXY_LIST y SAT_PROXY_STRATEGY del entorno.
+ */
+export const proxyManager = new ProxyManager();