Package net.jrodolfo.java_evolution.java19.structured_concurrency

package net.jrodolfo.java_evolution.java19.structured_concurrency
Explains Java 19 structured concurrency as the first incubator release.

The class name keeps the repository's historical PreviewNotes navigation, but the official Java 19 status was incubator. Read the package README for the parent-child task lifetime problem and the path toward later structured-concurrency modules.