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.

dependency-reduced-pom.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>org.example</groupId>
+  <artifactId>EndlessJumper</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <build>
+    <plugins>
+      <plugin>
+        <artifactId>maven-shade-plugin</artifactId>
+        <version>3.5.3</version>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>shade</goal>
+            </goals>
+            <configuration>
+              <transformers>
+                <transformer>
+                  <mainClass>eu.mhsl.minecraft.endlessjumper.EndlessJumper</mainClass>
+                </transformer>
+              </transformers>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+  <repositories>
+    <repository>
+      <id>spongepowered</id>
+      <url>https://repo.spongepowered.org/maven</url>
+    </repository>
+    <repository>
+      <id>jitpack</id>
+      <url>https://jitpack.io</url>
+    </repository>
+  </repositories>
+  <properties>
+    <maven.compiler.target>17</maven.compiler.target>
+    <maven.compiler.source>17</maven.compiler.source>
+  </properties>
+</project>