fix: restore Micronaut annotation processor auto-config in GrailsGradlePlugin

The annotation processor (micronaut-inject-java) is required for Java
sources that use Micronaut annotations like @ConfigurationProperties
and @singleton. Removing it broke the issue-11767 plugin's
PluginJavaMicronautBean, which depends on compile-time code generation.

Assisted-by: Claude Code <Claude@Claude.ai>

Author: jamesfredley

grails-gradle/plugins/src/main/groovy/org/grails/gradle/plugin/core/GrailsGradlePlugin.groovy

@@ -379,9 +379,10 @@ class GrailsGradlePlugin extends GroovyPlugin {
                 }
             }
 
-            // Micronaut annotation processors are not auto-configured here because they
-            // are incompatible with Groovy incremental compilation. See the Grails
-            // documentation for manual setup when Java sources use Micronaut annotations.
+            project.logger.info('Adding Micronaut annotationProcessor dependencies to project {}', project.name)
+            project.getDependencies().add('annotationProcessor', project.dependencies.platform("io.micronaut.platform:micronaut-platform:$micronautPlatformVersion"))
+            project.getDependencies().add('annotationProcessor', 'io.micronaut:micronaut-inject-java')
+            project.getDependencies().add('annotationProcessor', 'jakarta.annotation:jakarta.annotation-api')
 
             project.logger.info('Configuring CLASSIC boot loader for Micronaut compatibility in {}', project.name)
             project.tasks.withType(BootJar).configureEach { BootJar bootJar ->