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_group_tools/services/video.py

@@ -0,0 +1,22 @@
+import subprocess
+from pathlib import Path
+
+from nonebot_plugin_alconna import UniMessage
+
+
+def local_video(path: str) -> UniMessage:
+    """构造本地视频消息(覆盖 Media.__post_init__ 的 https 前缀规范化)"""
+    msg = UniMessage.video(url=path)
+    msg[0].url = path
+    return msg
+
+
+def get_video_info(url: str) -> str:
+    res = subprocess.run(["you-get", "-i", url], capture_output=True, text=True)
+    return res.stdout
+
+
+def download_video(url: str, filepath: Path, filename: str) -> None:
+    subprocess.run(
+        ["you-get", "-o", str(filepath), "-O", filename, url], capture_output=True
+    )