Update project configuration and refactor codebase

- Migrated Minestom dependency to new groupId.
- Added Maven Shade plugin for packaging.
- Switched Java version to 21 and corrected JDK settings.
- Refactored terrain generation logic to use the updated Minestom API.
- Replaced deprecated particle creation methods.
- Enabled Velocity proxy support.
- Updated various configuration files to align with the new build setup.

.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="" vcs="Git" />
+  </component>
+</project>