Set MODE=prod and bump frontend image

compose.yml

@@ -2,7 +2,7 @@ version: "3.8"
 
 services:
   web:
-    image: "ghcr.io/karrot-dev/karrot-docker-images:0.1.1-frontend"
+    image: "ghcr.io/karrot-dev/karrot-docker-images:0.1.2-frontend"
     configs:
       - source: nginx_config
         target: /etc/nginx/conf.d/default.conf
@@ -57,6 +57,7 @@ services:
       - "geoip_data:/var/lib/GeoIP"
       - "app_data:/app/uploads"
     environment:
+      - MODE=prod
       - MAXMIND_ACCOUNT_ID
       - EMAIL_BACKEND
       - EMAIL_FROM
@@ -112,6 +113,7 @@ services:
       - secret_key
       - smtp_password
     environment:
+      - MODE=prod
       - SITE_URL
       - SMTP_USER
       - SMTP_HOST