developer to build a tool for me

If you need a starter, https://github.com/dblock/slack-strava does that and more, and is open-source MIT license. Should take a dev a day's worth of work to fork and customize. Sorry not available to do that myself, but hope that helps.

I am associated with them, but there is a Zapier integration that supports Strava: https://zapier.com/apps/strava/integrations

You could use that create a Zap to write out to a DB, but you'd need the auth token from any athlete you wanted to track.