Support command directly

I installed the gstack skill pack in my project. I found that even with the example prompt from the README, the `/cso`、`/security-review` (gstack) skill in stack always takes over, and [security-audit-skill](https://github.com/cloudflare/security-audit-skill) never gets triggered. Auto-prompt is too unreliable; we should just support direct commands. for example:

```
/cloudflare-security-audit [prompt, guide...]
```

Start by reading the README example prompt and reproducing the case where /cso or /security-review takes over instead of security-audit-skill. Trace how the skill pack handles those prompts, then verify that `/cloudflare-security-audit [prompt, guide...]` directly triggers this skill and accepts the supplied guidance.

Written by the indexing model from the issue text.