chore: migrate edge-apps/instagram to standalone repo (Screenly/instagram-app)

[nicomiguelino]

Migrate edge-apps/instagram from the Playground monorepo to its own standalone repository at Screenly/instagram-app.

[nicomiguelino]

Closing as Won't Migrate. This app does not have a Screenly app ID assigned and is not ready for standalone migration. It will remain in the Playground monorepo for now.