Add gradle-wrapper.jar to the project

Adding the Gradle wrapper JAR file simplifies the build process for users by ensuring a consistent Gradle version. This inclusion helps maintain build compatibility and reduces setup friction for new contributors.

Jenkinsfile

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+pipeline {
+    agent any
+    stages {
+        stage('Gradle') {
+            steps {
+                sh 'bash gradlew build'
+            }
+        }
+        stage('Archive') {
+            steps {
+                archiveArtifacts artifacts: 'build/libs/', followSymlinks: false
+            }
+        }
+        stage('discord') {
+            when {
+                anyOf {
+                    branch 'main'
+                    branch 'master'
+                }
+            }
+            steps {
+                discordSend description: "Build: ${BUILD_NUMBER}", showChangeset: true, result: currentBuild.currentResult, title: currentBuild.fullProjectName, webhookURL: env.discordwebhook
+            }
+        }
+    }
+}