Gradle plugin: test source sets get no metamodel, and the javadoc task misses the preview flag

[zantvoort]

• StormPlugin wires only the configurations literally named ksp (storm-gradle-plugin/src/main/java/st/orm/gradle/StormPlugin.java:110) and annotationProcessor (:74). kspTest, testAnnotationProcessor and custom source sets get nothing, so entities declared in test sources silently have no metamodel, and nothing documents the limitation.
• --enable-preview is applied to JavaCompile, Test and JavaExec but not Javadoc (:81-86), so ./gradlew javadoc fails for Java projects.
• build.gradle.kts:26 claims Gradle 8.5+ support, but the functional tests never call withGradleVersion, so everything runs on the wrapper's version only. Add a small version matrix to the functional tests.