feat(wtfllm): 接入 nonebot-plugin-wtfllm AI 帮助助手

- pyproject 注册 nonebot_plugin_wtfllm 插件
- 新增 wtfllm_gate 插件:仅在群 621016172 启用 wtfllm 响应
- 新增 kb_build:抓取 danding.vip 文档并导入 wtfllm 知识库的脚本
- requirements: 升级 nonebot2 2.5.0 / pydantic 2.13.5,补 aiohttp 与 wtfllm 依赖

pyproject.toml

@@ -9,6 +9,6 @@ requires-python = ">=3.9, <4.0"
 adapters = [
     { name = "OneBot V11", module_name = "nonebot.adapters.onebot.v11" }
 ]
-plugins = ["nonebot_plugin_withdraw", "nonebot_plugin_saa"]
+plugins = ["nonebot_plugin_withdraw", "nonebot_plugin_saa", "nonebot_plugin_wtfllm"]
 plugin_dirs = ["danding_bot/plugins"]
 builtin_plugins = ["echo"]