feat: Upgrade dependencies, improve documentation, and remove examples from npm package
- Update package version to 1.2.0.
- Upgrade `mongodb` dependency to v6.17.0 and `zod` to v4.0.5.
- Update README.md to reflect the new MongoDB driver version requirement (v6+) and include instructions for upgrading MongoDB server.
- Remove `examples/` directory from the npm package by updating `.npmignore`.