feat(spring): @EnableStormRepositories for switching on repository scanning

[zantvoort]

Registering Storm repositories in plain Spring meant extending RepositoryBeanFactoryPostProcessor and overriding getRepositoryBasePackages(). That works, but it is not how Spring users expect to switch on a data library.

Fixes #201

What's included

• @EnableStormRepositories(basePackages/basePackageClasses, ormTemplateBeanName, repositoryPrefix) in storm-spring, mirroring @EnableJpaRepositories. Without explicit packages, the annotated class's package is scanned. One annotation serves both language stacks (storm-kotlin-spring depends on storm-spring, so it is one transitive hop away for Kotlin users): the imported registrar binds repositories through the language stack present on the classpath — the Kotlin adapter when storm-kotlin-spring is available, the Java adapter otherwise.
• Boot behavior: the annotation doubles as the explicit override — its registrar-provided post-processor makes the starter's auto-configured scanning back off through the existing @ConditionalOnMissingBean condition. Starter behavior without the annotation is unchanged.
• Configuring constructors on both adapters: RepositoryBeanFactoryPostProcessor(basePackages, ormTemplateBeanName, repositoryPrefix) in Java and Kotlin (named/default arguments), so multi-template applications define one bean per repository set instead of one subclass per domain. Subclassing keeps working unchanged.

Verification

• Full reactor green (13,706 tests).
• storm-spring: explicit packages, basePackageClasses, prefix bean naming, and default-package scanning through plain AnnotationConfigApplicationContexts.
• storm-kotlin-spring: the annotation on a Kotlin configuration registers the Kotlin adapter and repositories resolve through the KClass path.
• Java starter: with the annotation present, AutoConfiguredRepositoryBeanFactoryPostProcessor backs off.

Docs: both language tabs of spring-integration.md lead with the annotation, with the constructor-bean form documented for multi-template setups (Multiple Data Sources section updated to match); CHANGELOG entry covers the annotation and the constructors.