Initial project setup with Hytale plugin template

Add a minimal, ready-to-use Hytale plugin template including Gradle build scripts, GitHub Actions CI workflow, example plugin class, configuration and manifest files, and supporting documentation. This setup provides modern build tooling, automated server testing, and best practices for plugin development.

.gitignore

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+# Gradle
+.gradle/
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+.kotlin/
+
+# Server testing directory
+run/
+
+# IntelliJ IDEA
+.idea/
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+# Eclipse
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+# NetBeans
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+# VS Code
+.vscode/
+
+# Mac OS
+.DS_Store
+
+# Windows
+Thumbs.db
+desktop.ini
+
+# Logs
+*.log
+
+# Temporary files
+*.tmp
+*.bak
+*.swp
+*~