App details URL handling

[frnandu]

So that we can register android web links of format:

https://zapstore.dev/app/details?id=com.getalby.mobile

similarly like play store URLS,
even if we don't have there app details fetch from nostr events, but would be good to be able to distribute app buttons "Download on zapstore" with correct link, otherwise it might be too painful later to change them.

We can for now show/direct the same content as /download