fix: enter V8 isolate/context scope before editor codegen compile

[benpalevsky]

Problem

When the editor builds the TypeScript type definitions for your project, it runs a small piece of JavaScript through the V8 engine to compile it. Before V8 can compile anything, the code has to "enter" the right V8 isolate and context — basically telling V8 which JavaScript world to work in.

Two of these code paths forgot that step: the one that builds types for scene nodes (generate_scene_nodes_types) and the one that builds types for resources (generate_resource_types). They entered only a HandleScope, not the Isolate::Scope and Context::Scope. The third path that does the same kind of work (generate_types) enters all three and works fine.

The result: on a cold start, or when you reimport a lot of files at once, the editor crashes (segfault) deep inside V8's compile step.

What this changes

Add the two missing scope guards (v8::Isolate::Scope and v8::Context::Scope) at both sites, in the same positions as the path that already works (generate_types): the Isolate::Scope alongside the existing HandleScope, and the Context::Scope before the compile call. No logic changes — it just adds two stack guards per site, using the same isolate and context the surrounding code already had.

How to verify

Rebuild the engine and trigger a batch reimport (or a cold editor start that regenerates types) to confirm the crash is gone.

A changeset is included.

[Benjamin-Dobell]

This is a definite, yes, from me because I have this EXACT same patch locally and I really should have pushed it already, but it's currently sitting atop a local branch with much more dubious commits below it in stack. This regressed in a01cc6d.