Summary

• add Java/Kotlin repository detection and a dedicated JVM issue-implementation skill package
• select the JVM skill for traditional Java/Kotlin repos while keeping Gradle topology-aware skills for Gradle-shaped repos
• add prompt and guidance coverage for JVM build-tool, style, and secure-coding behavior

Validation

• go test ./internal/repo ./internal/skill
• go vet ./internal/repo ./internal/skill
• go test ./...

Closes #359