feat(npm): add publish_package_json macro for publishConfig field promotion

[kirkobyte]

Summary

• Adds a new publish_package_json convenience macro that mimics pnpm publish behavior: promotes fields from publishConfig into the top-level package.json and removes publishConfig
• Enables workspace packages to use publishConfig overrides (e.g. exports, main, types) that are applied when the package is linked as a dependency via npm_package
• Supports optional stamp_var to combine version stamping in a single target, and publish_config_fields to customize which fields are promoted (defaults to the pnpm allowlist)

Motivation

This could fix the long-standing issue of misalignment between in-IDE type resolution and resolution within Bazel. If pkg uses a package.json processed with this rule, we can use:

• IDE type resolution pointing to source file (e.g. src/index.ts)
• Published package (also resolved with publishConfig after feat(npm): use pnpm publish for npm_package #2868)
• Bazel type resolution pointing to output folder (e.g. dist/index.js)

Usage

load("@aspect_rules_js//npm:defs.bzl", "npm_package", "publish_package_json")

publish_package_json(
    name = "package",
    # Optional: stamp version at the same time
    # stamp_var = "STABLE_BUILD_VERSION",
)

npm_package(
    name = "pkg",
    srcs = [":lib", ":package"],
)

Test plan

• Example test in examples/publish_package_json/ verifies jq transform output
• E2e test in e2e/publish_package_json/ verifies a workspace consumer resolves through publishConfig.main (not source main)
• Existing stamped_package_json tests still pass