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

core/src/main/java/art/arcane/iris/platform/agent/Agent.java

@@ -29,6 +29,9 @@ public class Agent {
         installer.getMethod("retainClassLoader", ClassLoader.class);
         installer.getMethod("deferClassLoaderClose", ClassLoader.class);
         installer.getMethod("releaseClassLoader", ClassLoader.class);
+        installer.getMethod("trackServerStorage", Object.class);
+        installer.getMethod("serverStorageClosed", Object.class);
+        installer.getMethod("releaseServerStorage", Object.class);
     }
 
     public static void retainClassLoader(ClassLoader loader) {