statespace instruments

This origin runs the course's instruments (Z3, Spectacle, PGlite and the Mini-Plinth interpreter) in isolation from the main site. Untrusted input such as shared specs, imported receipts and learner-built wasm is parsed only here, and the two origins talk through messages alone (invariant I6, decision OD-5).

The course lives at github.com/praveer13/statespace.