Filter map by last commit date

Thank you so much for such a wonder project! Map of Github helps me discover new repositories relevant to my field. I avoid using unmaintained projects. The last commit time of a project's default branch is an indicator of whether or not its maintained. It would be helpful to have an optional filter to limit the map to just those repositories that have been updated in the last X years/months/weeks.

Start by tracing how repository data is fetched and how filters are applied to the map; the issue names no files or tests. Check whether the default branch's last commit date is available, then verify that an optional weeks, months, or years threshold limits the displayed repositories as intended.

Written by the indexing model from the issue text.