update: make improvements to containers

[codekow]

• run as user 1001
• remove bind mounts for src (issues with building on various platforms)
• /app as home
• add group write (g+w)
• use fqdn for FROM

[bugfest]

Thanks for your PR @codekow! FYI / we're working in additional optimizations at #49 - I'll check what's the best ordering for the merge

[lexfrei]

I suggest applying this after my PR because my PR is a little bit simpler and has already tested (by me)

[codekow]

Hopefully the PR isn't too much change. Mainly trying to move toward rootless and a consistent /app path. Thanks for the feedback. 👍