Use proper SQL concatenation

src/ddns_service/email.py

@@ -76,11 +76,10 @@ class EmailService:
             smtp_host = self.config["smtp_host"]
             smtp_port = self.config["smtp_port"]
 
-            server = smtplib.SMTP(smtp_host, smtp_port)
+            with smtplib.SMTP(smtp_host, smtp_port) as server:
                 if self.config.get("smtp_starttls", False):
                     server.starttls()
 
-            try:
                 if self.config.get("smtp_user"):
                     server.login(
                         self.config["smtp_user"],
@@ -89,8 +88,6 @@ class EmailService:
                 server.sendmail(msg["From"], [to], msg.as_string())
                 logging.info(f"Email sent: to={to} subject={subject}")
                 return True
-            finally:
-                server.quit()
 
         except Exception as e:
             logging.error(f"Email send failed: to={to} error={e}")

src/ddns_service/models.py

@@ -9,6 +9,7 @@ from peewee import (
     CharField,
     DateTimeField,
     DoesNotExist,
+    fn,
     ForeignKeyField,
     IntegerField,
     Model,
@@ -297,7 +298,7 @@ def get_hostname_for_user(hostname: str, user: User):
     Raises:
         DoesNotExist: If hostname not found or not owned by user.
     """
-    fqdn = Hostname.hostname + '.' + Hostname.zone
+    fqdn = fn.Concat(Hostname.hostname, '.', Hostname.zone)
     return Hostname.get((fqdn == hostname) & (Hostname.user == user))