Interactive kernels now release their memory

Every executed code cell compiles to an in-memory assembly. Until now those assemblies could never be unloaded — a portal running many interactive pages (a workshop, a course walkthrough, a long authoring session) accumulated them for its whole lifetime, slowing down progressively until navigations timed out.

Kernel sessions now load their script assemblies into a collectible context that is released when the session ends, and dynamically compiled node types were hardened the same way. Memory returns to baseline after your notebook pages close; long and busy sessions stay fast.