[optimize] support ESM exports of NPM

[Copilot]

web-utility exposed the right symbols in source, but published package entry resolution still fell back to CommonJS for bare ESM consumers. That caused Deno npm: imports like changeMonth to fail at module instantiation time.

• Package entrypoints

  • add a standard exports map for the root package
  • route ESM consumers to ./dist/index.mjs
  • keep CommonJS consumers on ./dist/index.js
  • preserve type resolution via ./dist/index.d.ts

• ESM artifact naming

  • switch the declared ESM entry from dist/index.esm.js to dist/index.mjs
  • align published metadata with the actual runtime expectation of Node/Deno ESM loaders

• Regression coverage

  • add a focused package-level test that locks the exported entrypoint contract in package.json

{
  "main": "dist/index.js",
  "module": "dist/index.mjs",
  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "import": "./dist/index.mjs",
      "require": "./dist/index.js",
      "default": "./dist/index.js"
    }
  }
}

[Copilot]

Pull request overview

This PR updates the published package entrypoint metadata so ESM consumers (including Deno npm: imports) resolve to an ESM build (dist/index.mjs) instead of falling back to CommonJS, and adds a regression test to lock the entrypoint contract.

Changes:

• Switch package.json "module" entry to dist/index.mjs and add an "exports" map routing import vs require to the correct artifacts.
• Add a package-level Jest test asserting the expected package.json entrypoint/export fields.
• Bump package version from 4.7.1 to 4.7.2.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
package.json	Adds an exports map and updates the ESM entry to dist/index.mjs (plus version bump).
test/package.spec.ts	Adds a regression test asserting the package entrypoint/export contract.

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