feat: add environment file support to Docker Compose

- Add env_file configuration to all services for automatic .env loading
- Enable consistent environment variable management across containers
- Support development, production, CLI, and test service configurations
- Maintain backward compatibility with existing environment overrides

docker-compose.yml

@@ -19,6 +19,8 @@ services:
       - /app/.venv # Exclude venv from bind mount
       - /app/backend/__pycache__ # Exclude cache
       - /app/.pytest_cache
+    env_file:
+      - .env
     environment:
       - DEBUG=true
       - LOG_LEVEL=debug
@@ -43,6 +45,8 @@ services:
     container_name: unitforge-prod
     ports:
       - "8080:8000"
+    env_file:
+      - .env
     environment:
       - DEBUG=false
       - LOG_LEVEL=info
@@ -68,6 +72,8 @@ services:
       - ./output:/output # Mount for output files
       - ./input:/input # Mount for input files
     working_dir: /app
+    env_file:
+      - .env
     networks:
       - unitforge-network
     profiles:
@@ -84,6 +90,8 @@ services:
       - .:/app
       - /app/.venv
       - test-results:/app/test-results
+    env_file:
+      - .env
     environment:
       - PYTHONPATH=/app/backend
     command:
@@ -114,6 +122,8 @@ services:
     volumes:
       - .:/app
       - /app/.venv
+    env_file:
+      - .env
     environment:
       - PYTHONPATH=/app/backend
     command: