更好的缓存，扬掉global，重构代码，整理聊天逻辑 (#16)

* 实现缓存装饰器，优化数据获取和存储逻辑

* 重构代码，准备将聊天请求逻辑移入MarshoHandler

* 记录点（

* unfinished

* 🎨 重写基本完毕

* 移除未使用import，添加漏掉的换行

nonebot_plugin_marshoai/instances.py

@@ -3,7 +3,7 @@ from nonebot import get_driver
 from openai import AsyncOpenAI
 
 from .config import config
-from .models import Cache, MarshoContext, MarshoTools
+from .models import MarshoContext, MarshoTools
 
 driver = get_driver()
 
@@ -11,7 +11,6 @@ command_start = driver.config.command_start
 model_name = config.marshoai_default_model
 context = MarshoContext()
 tools = MarshoTools()
-cache = Cache()
 token = config.marshoai_token
 endpoint = config.marshoai_azure_endpoint
 # client = ChatCompletionsClient(endpoint=endpoint, credential=AzureKeyCredential(token))