Improve readability of /skills list output

Problem

The formatting of the output from /skills list is difficult to scan and read.

Wrapped description lines are indented inconsistently. Some continuation lines align beneath the text so they remain visually associated with the bullet, while others begin at the far left. This makes it difficult to distinguish continuation text from the beginning of a new skill entry.

The skill name also does not stand out sufficiently from its description, and there is not enough visual separation between sections.

Suggested improvements

• Use consistent hanging indentation so every wrapped line aligns beneath the bullet text and never beneath the dash.
• Add clearer heading or separator formatting between sections.
• Make each skill name visually distinct from its description, such as bold text or placing the name on its own line.
• Consider rendering the list as a table with separate Name and Description columns.

Additional context

The normal feature-request link failed with an unhelpful error when opened under an Enterprise Managed User account:

https://github.com/github/copilot-cli/issues/new?template=feature_request.yml

The underlying issue was that Enterprise Managed Users cannot create issues in this public repository, but the web page did not expose that useful explanation.

首先定位 /skills list 命令以及渲染其输出的代码。比较换行后的描述和各节边界，然后统一格式，并验证技能名称在视觉上清晰可辨，且各条目仍然便于浏览。