Fix database scheme and introduce automatic database migration

src/ddns_service/app.py

@@ -7,7 +7,7 @@ import argon2
 
 from .dns import DNSService
 from .email import EmailService
-from .models import init_database
+from .models import create_tables, init_database
 from .ratelimit import RateLimiter
 
 
@@ -35,8 +35,9 @@ class Application:
         self.rate_limiter = None
 
     def init_database(self):
-        """Initialize database connection."""
+        """Initialize database connection and run migrations."""
         init_database(self.config)
+        create_tables()
         logging.debug("Database initialized")
 
     def init_dns(self):