feat(mail-service): Port-Konflikt behoben, SMTP-Konfig optimiert und dynamisches Plus-Addressing eingefügt

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

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

@@ -6,6 +6,7 @@ import jakarta.validation.Valid
 import jakarta.validation.constraints.Email
 import jakarta.validation.constraints.NotBlank
 import org.slf4j.LoggerFactory
+import org.springframework.beans.factory.annotation.Value
 import org.springframework.mail.SimpleMailMessage
 import org.springframework.mail.javamail.JavaMailSender
 import org.springframework.web.bind.annotation.*
@@ -45,6 +46,9 @@ class MailController(
 ) {
   private val logger = LoggerFactory.getLogger(MailController::class.java)
 
+  @Value("\${spring.mail.username}")
+  private lateinit var baseMailAddress: String
+
   @PostMapping("/nennung")
   fun receiveNennung(@Valid @RequestBody request: NennungRequest) {
     logger.info("Nennung via API erhalten: ${request.vorname} ${request.nachname} für Turnier ${request.turnierNr}")
@@ -70,7 +74,16 @@ class MailController(
     // Bestätigung an Reiter senden
     try {
       val message = SimpleMailMessage()
-      message.from = "online-nennen@mo-code.at"
+
+      // Dynamische Absenderadresse mit Plus-Addressing (z.B. online-nennen+26128@mo-code.at)
+      val dynamicFrom = try {
+        val (user, domain) = baseMailAddress.split("@")
+        "$user+${request.turnierNr}@$domain"
+      } catch (e: Exception) {
+        baseMailAddress
+      }
+
+      message.from = dynamicFrom
       message.setTo(request.email)
       message.subject = "Bestätigung: Ihre Online-Nennung für Turnier ${request.turnierNr}"
       message.text = """

backend/services/mail/mail-service/src/main/resources/application.yaml

@@ -11,19 +11,12 @@ spring:
       ddl-auto: update
     show-sql: true
   mail:
-    host: ${SPRING_MAIL_HOST:imap.world4you.com}
-    port: ${SPRING_MAIL_PORT:993}
+    host: ${SPRING_MAIL_HOST:smtp.world4you.com}
+    port: ${SPRING_MAIL_PORT:587}
     username: ${SPRING_MAIL_USERNAME:online-nennen@mo-code.at}
     password: ${SPRING_MAIL_PASSWORD:}
     properties:
       mail:
-        store:
-          protocol: imaps
-        imaps:
-          host: ${SPRING_MAIL_HOST:imap.world4you.com}
-          port: ${SPRING_MAIL_PORT:993}
-          ssl:
-            enable: true
         smtp:
           auth: ${SPRING_MAIL_PROPERTIES_MAIL_SMTP_AUTH:true}
           starttls: