inspect: add Temporal support

[Renegade334]

Example output:

> Temporal.Now.instant()
Temporal.Instant 2026-05-06T16:19:21.226404053Z

> class XYZ extends Temporal.Duration {}
> new XYZ(1, 2, 3, 4, 5, 6, 7, 8, 9)
XYZ [Temporal.Duration] P1Y2M3W4DT5H6M7.008009S

> Object.assign(Temporal.Now.zonedDateTimeISO('Pacific/Honolulu'), { foo: 'bar' })
Temporal.ZonedDateTime 2026-05-06T06:24:22.920191895-10:00[Pacific/Honolulu] {
  foo: 'bar'
}

The Temporal global obviously has to be lazily accessed, and there's no way to do it that's immune from potential user tampering. The approach taken here is just to fetch it from the global object every time, since the output of inspect() is inherently aimed at the human reader, so it doesn't really need to be particularly hardened.

WIP: tests

[ljharb]

i'm confused, why would it need to be lazily accessed instead of using primordials?

[legendecas]

the subsystem should be "util".

[Renegade334]

Alternative approach to the "how to Temporal" problem. This hooks into the pre-execution initializers and creates some typechecking functions and saves the constructor and prototype properties, primordial-ish, if Temporal exists.

We don't use this approach for any other ES builtins, only Node.js APIs, so does need consideration as to whether this is kosher. However, it does also provide for if we want to create or manipulate Temporal objects elsewhere in the API.