Suggested Labels [GA]

### Value Prop
The label picker now surfaces your most relevant labels at the top, so you can apply the right label in seconds instead of scrolling through hundreds of options. A "Suggested labels" group shows labels you've recently used alongside the most popular ones in the repo, each with a short reason so you always know why they appear. This makes labeling faster and more accurate, whether you're triaging a single issue or working through a backlog.

### Expected Outcome
Developers and maintainers spend less time hunting for the right label and more time doing meaningful work, resulting in better-labeled issues and pull requests across the board. By reducing choice fatigue in repos with large label sets, teams can triage more consistently and keep their workflows moving. Over time, smarter label suggestions help contributors get onboarded faster and keep project organization healthy with less manual effort.

路线图 issue 未指定任何仓库文件、测试或实现入口。以 Value Prop 和 Expected Outcome 作为产品需求开始；当建议的标签能够显示最近使用过的标签和热门标签及其原因，并减少标签搜索工作量时，工作即告完成。

由索引模型根据 Issue 内容生成。