Updated Iris packaging

- Version is 4.1.2-26.2 across platform builds
- Plugin builds use shared automatic jar selection
- Native adapters remain bundled in selected artifacts
- Plugin export tasks copy the selected artifact
- The previous plugin packer is removed
- The agent tracks primary storage closure during Spigot shutdown

buildSrc/build.gradle

@@ -31,7 +31,6 @@ tasks.named('test').configure {
 dependencies {
     implementation(gradleApi())
     implementation('org.ow2.asm:asm:9.10.1')
-    implementation('org.tukaani:xz:1.10')
     implementation('org.apache.commons:commons-compress:1.28.0')
     implementation('io.papermc.paperweight:paperweight-userdev:2.0.0-beta.21')
     testImplementation('junit:junit:4.13.2')