docs(readme): add status badges for CI, license, and versions

Add professional badges to README header showing:
- CI build status (GitHub Actions workflow)
- Apache 2.0 license
- Scala 2.13.14 and 2.12.18 support
- Spark 3.5.1 compatibility

This addresses ACTION_ITEMS quick win #9 (README: Build/CI Validates Badge)
and improves first impression for new users visiting the repository.

Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: derrickburns

README.md

@@ -1,4 +1,10 @@
-Generalized K-Means Clustering
+# Generalized K-Means Clustering
+
+[![CI](https://github.com/derrickburns/generalized-kmeans-clustering/actions/workflows/ci.yml/badge.svg)](https://github.com/derrickburns/generalized-kmeans-clustering/actions/workflows/ci.yml)
+[![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
+[![Scala 2.13](https://img.shields.io/badge/scala-2.13.14-red.svg)](https://www.scala-lang.org/)
+[![Scala 2.12](https://img.shields.io/badge/scala-2.12.18-red.svg)](https://www.scala-lang.org/)
+[![Spark 3.5](https://img.shields.io/badge/spark-3.5.1-orange.svg)](https://spark.apache.org/)
 
 🆕 DataFrame API (Spark ML) is the default.
 Version 0.6.0 introduces a modern, RDD-free DataFrame-native API with Spark ML integration.