Add Automatic-Module-Name manifest entry (#314)

Establishes a stable JPMS module name (org.codehaus.plexus.util) for
modular downstream consumers.

Fixes #311

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: gnodet

pom.xml

@@ -113,6 +113,7 @@ limitations under the License.
           <archive>
             <manifestEntries>
               <Multi-Release>true</Multi-Release>
+              <Automatic-Module-Name>org.codehaus.plexus.util</Automatic-Module-Name>
             </manifestEntries>
           </archive>
         </configuration>