### fix: 36 verbessere SMTP-Logging und Versionsmarker

- **dc-planb.yaml:** SMTP-Parameter hart codiert (Host, Port, Benutzer, Passwort).
- **mail-service:** Logging erweitert, SMTP-Konfiguration (`host`, `port`, `user`) wird angezeigt.
- **WebMainScreen:** Versionsmarker auf `v2026-04-23.36 - SMTP DIAGNOSE` aktualisiert.

backend/services/mail/mail-service/src/main/kotlin/at/mocode/mail/service/MailServiceApplication.kt

@@ -33,9 +33,14 @@ class MailServiceApplication(private val env: Environment) {
     val springPort = env.getProperty("server.port", "8083")
     val appName = env.getProperty("spring.application.name", "mail-service")
 
+    val mailHost = env.getProperty("spring.mail.host", "N/A")
+    val mailPort = env.getProperty("spring.mail.port", "N/A")
+    val mailUser = env.getProperty("spring.mail.username", "N/A")
+
     log.info("----------------------------------------------------------")
     log.info("Application '{}' is running!", appName)
     log.info("Spring Management Port: {}", springPort)
+    log.info("SMTP Config: host={}, port={}, user={}", mailHost, mailPort, mailUser)
     log.info("Profiles:               {}", env.activeProfiles.joinToString(", "))
     log.info("----------------------------------------------------------")
   }