feat: Improve auto-scanner robustness and instructions

Provide clearer instructions for users on how to keep the automated scanner running 24/7 by suggesting external scheduling services.
Refactor the server-side auto-scanner logic to use `runTransaction` for atomic updates of `lastAutoScan`, preventing potential race conditions and ensuring greater reliability.

server.ts

@@ -6,7 +6,7 @@ import * as OneSignal from 'onesignal-node';
 
 // Import Firebase (Server-side compatible since v9 supports Node environments)
 import { db } from "./src/lib/firebase";
-import { doc, getDoc, setDoc, addDoc, collection } from "firebase/firestore";
+import { doc, getDoc, setDoc, addDoc, collection, runTransaction } from "firebase/firestore";
 
 async function startServer() {
   const app = express();
@@ -133,10 +133,15 @@ _Analisado por Inteligência Institucional (Worker Node)_
       }
   };
 
-  setInterval(async () => {
+  const runAutoScannerJob = async () => {
     try {
       const settingsRef = doc(db, 'settings', 'app');
-        const settingsSnap = await getDoc(settingsRef);
+      let botToken = '';
+      let chatId = '';
+      let shouldExecute = false;
+
+      await runTransaction(db, async (transaction) => {
+        const settingsSnap = await transaction.get(settingsRef);
         if (!settingsSnap.exists()) return;
         
         const data = settingsSnap.data();
@@ -148,11 +153,16 @@ _Analisado por Inteligência Institucional (Worker Node)_
 
         // Check if enough time has passed based on interval
         if (now - lastScan >= intervalMins * 60 * 1000) {
+          // Atomic lock: update lastAutoScan inside transaction
+          transaction.update(settingsRef, { lastAutoScan: now });
+          shouldExecute = true;
+          botToken = data.telegramBotToken || '';
+          chatId = data.telegramChatId || '';
+        }
+      });
+
+      if (shouldExecute) {
         console.log("[Worker] Executing Auto-Scanner...");
-           
-           // Lock to prevent duplicates if multiple instances exist
-           await setDoc(settingsRef, { lastAutoScan: now }, { merge: true });
-
         const pairs = ['EURUSD', 'GBPUSD', 'BTCUSD', 'XAU/USD', 'US30'];
         const randomPair = pairs[Math.floor(Math.random() * pairs.length)];
         
@@ -169,15 +179,23 @@ _Analisado por Inteligência Institucional (Worker Node)_
             stopLoss: decision === 'BUY' ? '-15 pips' : '+15 pips',
         };
 
-           if (data.telegramBotToken && data.telegramChatId) {
+        if (botToken && chatId) {
-             await sendTelegramAlertServer(signalData, data.telegramBotToken, data.telegramChatId);
+          await sendTelegramAlertServer(signalData, botToken, chatId);
         }
         console.log(`[Worker] Sinais gerados e enviados para ${randomPair}`);
       }
     } catch (e) {
       console.error("[Worker] Erro no Auto-Scanner:", e);
     }
-  }, 60000); // Check every minute
+  };
+
+  setInterval(runAutoScannerJob, 60000); // Check every minute internally
+
+  app.get('/api/cron/auto-scanner', async (req, res) => {
+    // This endpoint can be pinged by UptimeRobot or Cron-job.org to prevent container sleep
+    await runAutoScannerJob();
+    res.json({ status: "ok", message: "Scanner check executed", timestamp: new Date().toISOString() });
+  });
 
   app.listen(PORT, "0.0.0.0", () => {
     console.log('Server running on http://localhost:' + PORT);

src/components/AdminDashboard.tsx

@@ -349,7 +349,7 @@ export const AdminDashboard: React.FC = () => {
                    </span>
                  </div>
                  <p className="text-[10px] text-brand-red font-bold">
-                   Atenção: Mantenha esta aba aberta para que o scanner automatizado (Robô Funcional no Browser) permaneça operando. Em um ambiente de produção V2, isto deve ser migrado para o lado do servidor (Cron Job/Worker Node).
+                   Atenção: A aplicação entra em repouso quando não há abas abertas. Para o Robô funcionar 24/7 de forma totalmente automática, utilize um serviço gratuito como o <strong>cron-job.org</strong> ou <strong>UptimeRobot</strong> para visitar a URL <code>{window.location.origin}/api/cron/auto-scanner</code> a cada 1 minuto.
                  </p>
                </div>
             )}