wger: set DJANGO_DB_DATABASE (2.6 dropped the sqlite default)

wger 2.6 crash-looped 15 times on a fresh deploy:

  django.core.exceptions.ImproperlyConfigured:
  Set the DJANGO_DB_DATABASE environment variable

The template already selected the sqlite3 engine, but 2.6 no longer supplies a
default database path -- it must be given explicitly even for sqlite. Pointed at
the existing wger_data volume (/home/wger/db) so the database survives redeploys.
Env var proven wrong by the deploy.

Campaign 7 catalog sweep.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Nn3VgQk9iwEGgyx6QJ2NvE

templates/wger/docker-compose.yml

@@ -16,6 +16,10 @@ services:
       - TZ=Europe/Budapest
       - SECRET_KEY=${SECRET_KEY}
       - DJANGO_DB_ENGINE=django.db.backends.sqlite3
+      # A wger 2.6 már NEM ad alapértelmezést ehhez, sqlite esetén sem: enélkül
+      # induláskor elszáll ("Set the DJANGO_DB_DATABASE environment variable").
+      # A wger_data kötetre mutat, hogy az adatbázis újratelepítést is túléljen.
+      - DJANGO_DB_DATABASE=/home/wger/db/database.sqlite
       - SITE_URL=https://${SUBDOMAIN}.${DOMAIN}
     volumes:
       - wger_data:/home/wger/db