chore: unify checkstyle, fix violations, cleanup bin/

build.gradle.kts

@@ -2,6 +2,7 @@ plugins {
     id("java")
     id("io.github.goooler.shadow") version("8.1.8")
     id("xyz.jpenilla.run-paper") version("3.0.2")
+    checkstyle
 }
 
 group = "dev.loki"
@@ -168,5 +169,20 @@ tasks {
     }
 }
 
+checkstyle {
+    toolVersion = "10.21.4"
+    configFile = file("config/checkstyle/checkstyle.xml")
+    isIgnoreFailures = false
+    maxErrors = 0
+    maxWarnings = 0
+}
+
+tasks.withType<Checkstyle>().configureEach {
+    reports {
+        xml.required.set(true)
+        html.required.set(true)
+    }
+}
+
 // Default task
 defaultTasks("clean", "build")