feat: 针对不同群聊设置模型类型、模式身份（上下文大小目前为冗余参数）

[MasterYang7]

群聊的上下文参数 目前没有应用到模型对话中

[MasterYang7]

dbmodel; CREATE TABLE "chatroom" ( "rd" integer PRIMARY KEY AUTOINCREMENT, "roomid" text, "name" text, "level" integer, "remark" text, "join_argot" text, "pat_return" text, "revoke_msg" text, "welcome_msg" text, "model_context" text, "model_history" integer, "model_default" text, "created_at" integer, "updated_at" integer );

CREATE UNIQUE INDEX "idx_chatroom_roomid" ON "chatroom" ( "roomid" ASC );