* Refactor: Modernize build and publishing workflow
- Upgraded Kotlin from 1.7.20 to 1.9.20.
- Upgraded JDK from 11 to 21 across all GitHub Actions workflows.
- Replaced the legacy `maven-publish` plugin with `com.vanniktech.maven.publish` for simplified publishing to Maven Central.
- Removed the `publishSnapshot.yml` workflow, as snapshot publishing is now managed by the new plugin.
- Updated `publishRelease.yml` to use the `publishToMavenCentral` task and new secrets (`MAVEN_CENTRAL_USERNAME`, `MAVEN_CENTRAL_PASSWORD`).
- Simplified `build.gradle.kts` by removing manual publishing and signing logic.
- Set the JVM target to "21".
- Bumped the project version to `3.1.1`.
- Removed `js` targets and related configurations.
- Added a new code style configuration file for the project (`.idea/codeStyles/Project.xml`).
* fix: Add JavaScript targets
- Added JS (IR) targets (`browser` and `nodejs`) to the Kotlin Multiplatform configuration for publishing.
* Improve README and document new publishing workflow
- Expanded the project description to highlight key features like Kotlin Multiplatform support, traversal iterators, DSL, and utility functions.
- Added a new "Installation" section with instructions for Gradle (Kotlin/Groovy) and Maven.
- Added a "Traversal and utilities" section to demonstrate usage of iterators and helper functions.
- Replaced the old publishing documentation with updated instructions for publishing to Maven Central via the Central Portal.
- Detailed the two publishing methods: automatically via GitHub Actions on release and manually via local Gradle commands.
- Clarified required secrets and environment variables for the new publishing process.
- Updated build script to support publishing to Sonatype's s01.oss.sonatype.org, which is compatible with the new Maven Central Portal.
- Prioritized Central Portal credentials (CENTRAL_USERNAME, CENTRAL_PASSWORD) over legacy OSSRH credentials.
- Updated repository URLs for releases and snapshots to point to s01.oss.sonatype.org.
- Added documentation in README.md explaining the new publishing setup, environment variables, and Gradle tasks.
