fix(client): unwrap constructors to primitives in type mapping

[watersRand]

Description

Resolves: #2987

This pull request fixes a type inference bug where using global constructors (like String, Number, or Boolean) in .withTypeMapping() resulted in incorrect return types, specifically appearing as string | {} or number | {} instead of the expected primitives.

The Problem:
When a user provides String (the StringConstructor) to the mapping, TypeScript's infer keyword in ReplyWithTypeMapping captures the interface String (the object wrapper) rather than the primitive string. Because this interface is a non-null object, it is often represented as {} in type unions, leading to the confusing string | {} signature for commands like hGet.

The Solution:
I introduced an UnwrapConstructor<T> utility type that explicitly maps global constructors to their primitive counterparts:

• StringConstructor → string
• NumberConstructor → number
• BooleanConstructor → boolean
• BigIntConstructor → bigint

This ensures that the Extract logic within the mapping correctly identifies the intended primitive type.

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Checklist

• Does npm test pass with this change (including linting)?
• Is the new or changed code fully tested?
• Is a documentation update included? (N/A - Fixes existing type behavior)

[nkaradzhov]

@watersRand thanks for this PR, much appreciated. I will need to check TS performance, as we already have a big issue, so hopefully this doesnt add to it. Will keep in touch.

[nkaradzhov]

@watersRand i made a PR with some fixes, please review and merge it, so we can close this one :)