Chore: Improve Docker deployment configuration

- Use environment variables in docker-compose for secrets/paths
- Add .env.example template for required variables
- Add .env to .gitignore to prevent secret exposure
- Add docker-build-and-push.cmd helper script

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -1,15 +1,13 @@
 services:
   moneymap:
-    build:
-      context: ./MoneyMap
-      dockerfile: Dockerfile
+    image: ${DOCKER_IMAGE:-yourusername/moneymap:latest}
     container_name: moneymap
     ports:
       - "5010:5010"
     environment:
-      - ConnectionStrings__MoneyMapDb=Server=barge.lan;Database=MoneyMap;User Id=moneymap;Password=YOUR_PASSWORD;TrustServerCertificate=True;
-      - Receipts__StoragePath=/app/receipts
+      - ConnectionStrings__MoneyMapDb=Server=${DB_SERVER};Database=MoneyMap;User Id=${DB_USER};Password=${DB_PASSWORD};TrustServerCertificate=True;
+      - Receipts__StoragePath=receipts
       - OPENAI_API_KEY=${OPENAI_API_KEY}
     volumes:
-      - /mnt/docker-data/moneymap/receipts:/app/receipts
+      - ${RECEIPTS_HOST_PATH}:/app/wwwroot/receipts
     restart: unless-stopped