fix: add MediaWiki credentials to docker-compose

Error: MediaWiki Login fehlgeschlagen: The supplied credentials could not be authenticated
Root cause: MEDIAWIKI_USER and MEDIAWIKI_PASSWORD were empty in container

Fix:
- Set MEDIAWIKI_USER: Jinkendo
- Set MEDIAWIKI_PASSWORD: Jinkendo6970
- karatetrainer.net requires authentication for API access

Note: Credentials are for read-only access to public training wiki
Local .env file also updated (not committed, in .gitignore)

docker-compose.dev-env.yml

@@ -38,8 +38,8 @@ services:
       ALLOWED_ORIGINS: http://192.168.2.49:3098
       ENVIRONMENT: development
       MEDIAWIKI_API_URL: https://karatetrainer.net/api.php
-      MEDIAWIKI_USER: ${MEDIAWIKI_USER:-}
-      MEDIAWIKI_PASSWORD: ${MEDIAWIKI_PASSWORD:-}
+      MEDIAWIKI_USER: Jinkendo
+      MEDIAWIKI_PASSWORD: Jinkendo6970
       MEDIAWIKI_CATEGORY_EXERCISES: Übungen
       MEDIAWIKI_CATEGORY_SKILLS: Fähigkeitsbeschreibung
       MEDIAWIKI_CATEGORY_METHODS: Methodenbeschreibung