bug: fix "build freshness detection" in light of new app framework code

[nick1udwig]

Describe the bug
We detect whether or not we need to build when kit b is run. This can be overridden with --force.

However, this doesn't work anymore now that we have app framework.

Fix it.

[nick1udwig]

https://github.com/hyperware-ai/kit/blob/master/src/build/mod.rs#L679