Allow discovery of teams configuration files in subfolders

* Perhaps use a configurable glob style syntax for discovery?
* https://docs.microsoft.com/en-us/dotnet/core/extensions/file-globbing#get-all-matching-files
* Must flatten full list to validate no duplicates
* If duplicate detected, fail operation
* Failure of an operation would be reported either by the Action or the GitHub App as a commit/PR status. Do not embed reporting logic in Core

Why allow this? To leverage CODEOWNERS as a means to delegate trust for team creation

首先定位当前的团队配置发现入口，并跟踪配置文件的加载和验证方式。明确预期的 glob 行为、扁平化和重复检测规则，然后确认错误报告仍位于 Core 之外，如 issue 中所述。

由索引模型根据 Issue 内容生成。