feat(dev-server): `inspect` (Node debug protocol forwarding)

[lukekania]

Goal

Honor inspect (e.g. inspect: true or inspect: '127.0.0.1:9229') to forward Node's --inspect flag through to any subprocess the dev server spawns. Mostly useful when ngc-rs eventually supports SSR (out of scope for v1.0).

Current state

Silently dropped. Low impact — the only Node subprocess ngc-rs spawns is the optional PostCSS/Tailwind invocation, which doesn't typically benefit from a debugger.

Scope

• Schema field + option pass-through, but the actual semantics depend on what subprocesses we have to debug. Until SSR lands, this is mostly a no-op stub that just doesn't error on the option.

Definition of done

• inspect: true no longer triggers a "silently overridden" warning.
• A future SSR implementation can wire this through trivially.