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_huoziyinshua/HuoZiYinShua/settings.json

@@ -0,0 +1,6 @@
+{
+	"sourceDirectory": "./HuoZiYinShua/sources/",
+	"ysddSourceDirectory": "./HuoZiYinShua/ysddSources/",
+	"dictFile": "./HuoZiYinShua/dictionary.json",
+	"ysddTableFile": "./HuoZiYinShua/ysddTable.json"
+}