Stateful testing

[AlexeyRaga]

• Add State Machine Property Based testing library (and docs about what it is and how to use it)
• Make API Reference render in both C# and F#
• Add missing extension methods for Property for C# (around rendering reports, no functional or impactful changes in the core lib)

[moodmosaic]

Thank you! This is a massive and well-architected addition. I did a first pass and it looks great overall.

I’ll do a deeper review, but my initial read suggests a few small-but-important issues around isLinearizable and the parallel path that might need tightening (identity/consumption of outputs, starting state, and Ensure/Require handling).

I’ll follow up with more detail soon.