Migrate to new Hytale plugin template structure

Replaces the previous Kotlin-based Gradle build and template files with a new Java-based Gradle build system and updated example plugin code. Removes old build scripts, plugin template, and configuration, and introduces a new ExamplePlugin with updated manifest, command, and recipe example. Updates documentation and project configuration to match the new structure and usage.

.gitignore

@@ -1,15 +1,14 @@
-# Gradle
-.gradle/
+### Gradle ###
+.gradle
 build/
 !gradle/wrapper/gradle-wrapper.jar
 !**/src/main/**/build/
 !**/src/test/**/build/
-.kotlin/
 
-# Server testing directory
+### Hytale ###
 run/
 
-# IntelliJ IDEA
+### IntelliJ IDEA ###
 .idea/
 *.iws
 *.iml
@@ -18,7 +17,7 @@ out/
 !**/src/main/**/out/
 !**/src/test/**/out/
 
-# Eclipse
+### Eclipse ###
 .apt_generated
 .classpath
 .factorypath
@@ -30,28 +29,15 @@ bin/
 !**/src/main/**/bin/
 !**/src/test/**/bin/
 
-# NetBeans
+### NetBeans ###
 /nbproject/private/
 /nbbuild/
 /dist/
 /nbdist/
 /.nb-gradle/
 
-# VS Code
+### VS Code ###
 .vscode/
 
-# Mac OS
-.DS_Store
-
-# Windows
-Thumbs.db
-desktop.ini
-
-# Logs
-*.log
-
-# Temporary files
-*.tmp
-*.bak
-*.swp
-*~
+### Mac OS ###
+.DS_Store