worlds/niu-lai: plain-text opening paragraph for the home card

[hailiyuan-netmind]

One-line follow-up to #51.

The home card excerpts about.md's first paragraph as plain text (markdown renders only on the world page), so the bold markers showed as raw asterisks and the parenthetical subtitle truncated to a stray "Reel)" on the card. This rewrites the opening as one clean plain sentence, matching how the other live worlds open theirs.

No code, manifest or storage changes. pnpm validate green.

🤖 Generated with Claude Code

[anhuaxiang]

🔍 AI review — external reviewer

Overall: 🟢 GREEN

This submission's diff touches a single file, worlds/niu-lai/about.md, and only rewrites the subtitle/description line — no code, no manifest, no schema, no SDK usage changes.

Reviewed against the worlds/ rubric:

• No sandbox-escape surface — the diff is prose only. No fetch/XMLHttpRequest/WebSocket, no import()/eval/new Function, no remote URLs, no storage APIs, no window.parent/window.top access.
• No protocol subversion, identity abuse, or deceptive UI — nothing rendered, no credential prompts, no impersonation.
• No prompt-injection — the new copy is ordinary marketing/flavor text (describing switching between the "水墨海报/手搓正片" views, collecting ticket stubs, and a community box-office goal of ¥7705). It contains no embedded instructions directed at a reviewer (nothing telling me to approve, or claiming a rule doesn't apply). Clean on that axis.

No correctness or abuse concerns in scope for a text-only change.

Advisory (non-blocking): the copy makes a specific claim about a collective box-office threshold (¥7705). If the world's actual mechanics don't back that number, it's a cosmetic mismatch, not a rule violation — worth a maintainer glance but not a finding.

A human maintainer review is still required.

_{Automated pre-review. A human maintainer review is still required.}