chore: avoid unconditional db.create_all(); prefer Flask-Migrate when migrations/ exists

app.py

@@ -5,6 +5,7 @@ import re
 from utils import generate_vcard
 import logging
 from logging.handlers import RotatingFileHandler
+from flask_migrate import Migrate
 
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
 DB_PATH = os.path.join(BASE_DIR, 'anmeldung.db')
@@ -14,6 +15,8 @@ app.config['SQLALCHEMY_DATABASE_URI'] = f'sqlite:///{DB_PATH}'
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
 
 db = SQLAlchemy(app)
+# Flask-Migrate (Alembic) integration
+migrate = Migrate(app, db)
 
 # --- logging setup -------------------------------------------------
 LOG_DIR = os.path.join(BASE_DIR, 'logs')
@@ -135,7 +138,12 @@ def danke():
 
 
 if __name__ == '__main__':
-    # Ensure DB exists
-    if not os.path.exists(DB_PATH):
+    # In development only: if there is no migrations directory, create tables automatically.
+    # In all other cases prefer using Flask-Migrate (flask db upgrade).
+    migrations_dir = os.path.join(BASE_DIR, 'migrations')
+    if not os.path.exists(migrations_dir):
+        app.logger.info('No migrations directory found; creating database tables with db.create_all()')
         db.create_all()
+    else:
+        app.logger.info('Migrations directory present; please use "flask db upgrade" to update the database schema')
     app.run(debug=True)