add JaCoCo coverage reporting for SonarQube

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

backend/build.gradle.kts

@@ -1,5 +1,6 @@
 plugins {
 	java
+	jacoco
 	id("org.springframework.boot") version "4.1.0"
 	id("io.spring.dependency-management") version "1.1.7"
 	id("org.sonarqube") version "7.3.0.8198"
@@ -18,6 +19,8 @@ sonar {
   properties {
     property("sonar.projectKey", "Vaessl")
     property("sonar.projectName", "Vaessl")
+    property("sonar.coverage.jacoco.xmlReportPaths",
+      "${layout.buildDirectory.get()}/reports/jacoco/test/jacocoTestReport.xml")
   }
 }
 
@@ -62,14 +65,9 @@ tasks.withType<JavaCompile> {
 	options.compilerArgs.add("-parameters")
 }
 
-tasks.withType<Test> {
-	useJUnitPlatform()
-}
-
 tasks.withType<Test> {
     useJUnitPlatform()
-    
+    finalizedBy(tasks.jacocoTestReport)
-    // log exact test failures, standard out, and errors in CI
     testLogging {
         events("failed", "standardError")
         exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
@@ -78,3 +76,10 @@ tasks.withType<Test> {
         showStackTraces = true
     }
 }
+
+tasks.jacocoTestReport {
+    dependsOn(tasks.withType<Test>())
+    reports {
+        xml.required = true
+    }
+}