Add captive portal

[saoron]

The portal will open the app if installed or point to the store to get the app,
The portal could trigger background script for update/upload or any idle action.

[Erim32]

Hello, for the first part you can edit the hostapd system and add a rule in IP Table:
Something like that:
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to-destination 127.0.0.1:80
(not sure, check https://raspberrypi.stackexchange.com/questions/58026/open-splash-page-after-connecting-to-wifi-hotspot)
That require to integrate apache.
In the index.js page, run a JavaScript Script who gonna call the URI of the app.
Note: that also require to add URI in apps.