Add HeXi bot codebase: custom plugins, web frontends, tests

- hexi core: message handling, rate limiting, cooldown, plugin manager
- Custom plugins: BF stats, daily check-in, quotes, persona cards, etc.
- Community plugins vendored under hexi/plugins with local fixes
- Web admin frontends (learning-chat, persona-admin), unified hexi/web
- Tests for rate_limit/cooldown/memes/persona; poetry.lock

Co-Authored-By: Claude <noreply@anthropic.com>

hexi/plugins/nonebot_plugin_helldivers_tools/data/font/HD2S字体包/安装前须知.txt

@@ -0,0 +1,7 @@
+字体仅作为社区分享参考作用 侵权请联系
+如需字体授权请前往字体对应厂商进行联系
+
+字体使用建议:
+简单字重原理介绍
+字重决定了画面中文字的视觉比重 字重越大越被容易注意
+即 文字越大字重越重 文字越细字重越小