feat：新增自动表达优化功能，优化表达方式的提取

src/common/database/database_model.py

@@ -321,12 +321,7 @@ class Expression(BaseModel):
 
     situation = TextField()
     style = TextField()
-
-    # new mode fields
-    context = TextField(null=True)
-
     content_list = TextField(null=True)
-    style_list = TextField(null=True)  # 存储相似的 style，格式与 content_list 相同（JSON 数组）
     count = IntegerField(default=1)
     last_active_time = FloatField()
     chat_id = TextField(index=True)