feat(events): migrate distribution to Java 25 and Purpur

BREAKING CHANGE: New releases require Java 25/Purpur 26.2 and use purpur-event-producer-<version>.jar. Runtime SpigotEventProducer identity, server UUID, SQLite outbox and CloudEvent delivery contracts remain unchanged. Replace the old JAR rather than installing both distributions.

build.gradle.kts

@@ -9,12 +9,12 @@ version = providers.gradleProperty("releaseVersion")
 
 repositories {
     mavenCentral()
-    maven("https://hub.spigotmc.org/nexus/content/repositories/snapshots/")
+    maven("https://repo.purpurmc.org/snapshots/")
 }
 
 java {
     toolchain {
-        languageVersion = JavaLanguageVersion.of(17)
+        languageVersion = JavaLanguageVersion.of(25)
     }
 }
 
@@ -23,10 +23,10 @@ tasks.withType<JavaCompile>().configureEach {
 }
 
 dependencies {
-    compileOnly("org.spigotmc:spigot-api:26.2-R0.1-SNAPSHOT")
+    compileOnly("org.purpurmc.purpur:purpur-api:26.2.build.2618-stable")
     implementation("org.xerial:sqlite-jdbc:3.50.3.0")
 
-    testImplementation("org.spigotmc:spigot-api:26.2-R0.1-SNAPSHOT")
+    testImplementation("org.purpurmc.purpur:purpur-api:26.2.build.2618-stable")
     testImplementation(platform("org.junit:junit-bom:5.13.4"))
     testImplementation("org.junit.jupiter:junit-jupiter")
     testRuntimeOnly("org.junit.platform:junit-platform-launcher")
@@ -34,6 +34,9 @@ dependencies {
 
 tasks.test {
     useJUnitPlatform()
+    dependsOn(tasks.jar)
+    systemProperty("distribution.jar", tasks.jar.get().archiveFile.get().asFile.absolutePath)
+    systemProperty("distribution.version", project.version.toString())
 }
 
 val pluginVersion = version