refactor(settings): simplify environment toggle to use DEV variable only

backend/config/settings.py

@@ -28,9 +28,8 @@ load_dotenv(BASE_DIR.parent / '.env')
 SECRET_KEY = os.getenv('DJANGO_SECRET_KEY', 'django-insecure-@8*97xo5!gdi!x*94-%n8$b63%ljy#@&^#7$h!9v-4a2#r+98t')
 
 # Environment setup (development / production)
-# Reads DEV=True/False or ENVIRONMENT='development'/'production'
-ENVIRONMENT = os.getenv('ENVIRONMENT', os.getenv('DJANGO_ENV', 'development')).lower()
-IS_DEV = os.getenv('DEV', 'True' if ENVIRONMENT in ('development', 'dev') else 'False').lower() in ('true', '1', 't')
+# Reads DEV=True for development, DEV=False for production
+IS_DEV = os.getenv('DEV', 'True').lower() in ('true', '1', 't')
 
 if IS_DEV:
     DEBUG = True