localization for ntfy and mail

docker-compose.yml

@@ -31,6 +31,8 @@ services:
       # - MAIL_USE_TLS=true
       # - MAIL_FROM=contract-monitor@example.com
       # - MAIL_TO=you@example.com
+      # - APP_EXTERNAL_URL=https://contracts.example.com
+      # - APP_LOCALE=en
       # Optional: festen iCal-Token vorgeben
       # - ICAL_SECRET=replace-with-secret
     volumes:
@@ -39,7 +41,8 @@ services:
       - "8080:8000"
   contract-companion-ui:
     build:
-      context: ./frontend
+      context: .
+      dockerfile: frontend/Dockerfile
     container_name: contract-companion-ui
     restart: unless-stopped
     ports: