Provisions the node_modules tree esbuild resolves runtime JS bundles against.

MishkaCmsCore.Runtime.Compilers.JavaScriptCompiler emits an entry file that does import { Socket } from "phoenix", and esbuild resolves those bare specifiers through NODE_PATH — config/test.exs points it at priv/static/temp/js_assets/node_modules. A host fills that directory as part of its asset build (the CMS keeps checked-in copies); running on our own, nothing does, and every JS compilation fails with Could not resolve "phoenix".

So the harness fills it from deps/, where each of these packages already ships a prebuilt CommonJS bundle — the same code the CMS vendored, read from the version this suite actually depends on rather than a copy that can drift. Only the packages the generated entry file imports are provisioned; phoenix-colocated is not among them because the compiler writes that one itself.

Called once at boot by MishkaCmsCore.Test.Boot (its js_assets: option), before any test compiles JS. The directory is the one the suite's esbuild NODE_PATH names: core's own by default, an extension's under its own priv/static/temp/js_assets/node_modules.