fix: resolve smtp authentication error and notification issues

- Stripped literal quotes from SMTP credentials in nodemailer config to prevent '535 Incorrect auth data' in Docker Swarm.

- Reduced notification polling interval from 60s to 10s for real-time updates.

- Fixed browser autoplay block for audio notifications by properly initializing the audio context.

backend/index.js

@@ -19,8 +19,8 @@ const transporter = nodemailer.createTransport({
   port: parseInt(process.env.SMTP_PORT) || 587,
   secure: false, // false para 587 (STARTTLS)
   auth: {
-    user: process.env.SMTP_USER || 'nao-responda@blyzer.com.br',
-    pass: process.env.SMTP_PASS || 'Compor@2017#', // Fallback to your known prod pass if env fails in swarm
+    user: (process.env.SMTP_USER || 'nao-responda@blyzer.com.br').replace(/^"|"$/g, ''),
+    pass: (process.env.SMTP_PASS || 'Compor@2017#').replace(/^"|"$/g, ''),
   },
   tls: {
     ciphers: 'SSLv3',