add Just integration

it would be interesting to integrate into Just somehow so that people can define a reconciliation recipe in such a way that actually all the operations and perhaps even the storage engine is implemented through just.

Something like:

- a just recipe lists the current stored set
- a just recipe stores the current set
- another just recipe defines the desired set
- ideally there are simple ways to derive the first 2 for all really useful use cases
- desired set could be defined either using tauler's JSX-like system, or maybe some rhai-base scripting tool that integrates well with just
- some magic from the optative integration layer takes care of the diff logic
- lifecycle operations for each individual item are also defined by just recipes
- somehow these need to be "scoped" or "namespaced" so that multiple such

An interesting use case example for this could perhaps be a rule that forces test files to be located in a certain way. Perhaps force vitest in-source testing to be used when the tests are shorter than N lines, separate file to be used otherwise.