[AI Triage] Weekly refresh knowledge base sources for each repository

To keep knowledge base content fresh, we'll need to create a scheduled job of some sort to refresh the index for each repository on a weekly basis.

No files, tests, or entry points are identified in the issue. First clarify how repository knowledge-base sources are currently indexed and where scheduled work belongs; done means a weekly job refreshes the index for each repository and its behavior is verified.

Written by the indexing model from the issue text.