feat: Add jest and codecov integrations

[Sirivasv]

No description provided.

[Copilot]

Pull Request Overview

This PR adds Jest testing framework and Codecov integration to replace the existing custom test setup. The changes migrate from a simple console-based test to a proper Jest test suite with code coverage reporting.

• Replaces custom test runner with Jest testing framework
• Adds code coverage collection and Codecov integration
• Updates the printMessage function to return values instead of logging

Reviewed Changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
test/main.test.js	New Jest test file replacing the old custom test
test/main.js	Removes the old custom test implementation
src/bmssp.mjs	Changes printMessage to return instead of console.log
package.json	Adds Jest dependency and updates test script
jest.config.mjs	Adds comprehensive Jest configuration
.github/workflows/npm-build.yml	Integrates Codecov upload step

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