🔧 chore(env): update database path in environment files

- change DATABASE_PATH in .env-example and docker-compose.yml
- ensure consistency with Dockerfile for app directory structure

📦 build(docker): adjust Dockerfile for new data directory

- create /app/data directory for database storage
- update DATABASE_PATH environment variable accordingly

📝 docs(README): update README for German localization

- replace English sections with German equivalents
- adjust setup instructions to match new environment configurations

Dockerfile

@@ -14,7 +14,8 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 COPY app ./app
 
-ENV DATABASE_PATH=/data/fleetledger.db
+RUN mkdir -p /app/data
+ENV DATABASE_PATH=/app/data/fleetledger.db
 
 EXPOSE 8000