feat: publish npm package on release

[garciasdos]

Build and Publishing Workflow Improvements:

• Added a new GitHub Actions workflow (publish.yml) to automate publishing the package to npm when a new tag is pushed. This workflow uses Node.js 22 and ensures the package is built before publishing.
• Updated the Node.js version used in CI workflows from 20 to 22 for better compatibility and future-proofing.

Package Structure and Publishing:

• Renamed the package in package.json to @postman/postman-mcp-server, set the main entry point to dist/src/index.js, defined the bin field, and specified which files should be included when publishing to npm. Also added a prepack script to ensure the package is built and synced before publishing, and set the package to be public.
• Added a .npmignore file to exclude source, test, development, and configuration files from the npm package, ensuring only the necessary distribution files are published.

Code and Configuration Updates:

• Changed the shebang in src/index.ts from tsx to node to ensure compatibility when running the built JavaScript file directly.
• Updated ESLint configuration to ignore the dist directory and all .js files, preventing linting of build artifacts.