fix(build): development declaration stubs

[yaacovCR]

Description

This fixes TypeScript resolution for the package’s development export condition when consumers use moduleResolution: "node16".

Before this change, the generated development declaration stubs always re-exported the ESM entrypoint:

// __dev__/index.d.ts
export * from '../index.mjs';

That worked for ESM declaration stubs, but it broke CommonJS TypeScript consumers. In a .cts project using:

{
  "compilerOptions": {
    "customConditions": ["development"],
    "module": "node16",
    "moduleResolution": "node16"
  }
}

TypeScript resolves graphql through the development condition to the CommonJS dev entrypoint, then reads __dev__/index.d.ts. Because that .d.ts re-exported ../index.mjs, TS reported:

error TS1479: The current file is a CommonJS module whose imports will produce 'require' calls;
however, the referenced file is an ECMAScript module and cannot be imported with 'require'.

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