fix(commands): correct misleading description in sentient.md

[xiaolai]

Automated audit: This PR was generated by NLPM, a natural language programming linter, running via claude-code-action. Please evaluate the diff on its merits.

Bug / Security Finding (Medium)

`sentient.md` has this frontmatter description:

```
description: Manage, organize and ships your codebase.
```

But the command body is a documented hook-blocking demo that instructs Claude to run `rm -rf` in three variations:

"Run 3 variations of the `rm -rf` command against this codebase."

This mismatch has two concrete consequences:

1. Misrouting: Claude Code uses `description` for agent auto-dispatch and command selection. A description advertising general codebase management will cause the command to be selected in contexts where a destructive demo is not appropriate.
2. User surprise: Anyone cloning this repo who enables the command without reading the full body will invoke destructive operations believing it to be a safe utility — the only safeguard being that `pre_tool_use.py` must already be active.

The file itself clearly acknowledges its demo nature in the body (`# Sentient`, "Test prompt to showcase claude code hook blocking a dangerous rm -rf command. This is for demo purposes only."). The description just needs to match.

Fix

```diff
-description: Manage, organize and ships your codebase.
+description: "Demo: tests hook blocking of destructive rm -rf commands — not for production use"
```

No logic, instructions, or hook behavior changed.