Ensure LIGHTEN work (#3542)

### What problem does this PR solve?
#3531

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/settings.py

 
 
 def init_settings():
-    global LLM, LLM_FACTORY, LLM_BASE_URL
+    global LLM, LLM_FACTORY, LLM_BASE_URL, LIGHTEN, DATABASE_TYPE, DATABASE
+    LIGHTEN = int(os.environ.get('LIGHTEN', "0"))
+    DATABASE_TYPE = os.getenv("DB_TYPE", 'mysql')
+    DATABASE = decrypt_database_config(name=DATABASE_TYPE)
     LLM = get_base_config("user_default_llm", {})
     LLM_FACTORY = LLM.get("factory", "Tongyi-Qianwen")
     LLM_BASE_URL = LLM.get("base_url")