Fix install-package-422 test to not depend on external packages.linkeddatahub.com

Use a local URL for the nonexistent package URI so the test doesn't fail when
the external server is unreachable. Also catch NotFoundException and
ProcessingException in getPackage() so any HTTP/connection failure reliably
returns null and triggers the 422 response.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: namedgraph

http-tests/admin/packages/install-package-422.sh

@@ -13,6 +13,6 @@ curl -k -w "%{http_code}\n" -o /dev/null -s \
   -E "$OWNER_CERT_FILE":"$OWNER_CERT_PWD" \
   -X POST \
   -H "Content-Type: application/x-www-form-urlencoded" \
-  --data-urlencode "package-uri=https://packages.linkeddatahub.com/nonexistent/#package" \
+  --data-urlencode "package-uri=${END_USER_BASE_URL}static/nonexistent/#package" \
   "${ADMIN_BASE_URL}packages/install" \
 | grep -q "$STATUS_UNPROCESSABLE_ENTITY"

src/main/java/com/atomgraph/linkeddatahub/resource/admin/pkg/InstallPackage.java

@@ -55,6 +55,8 @@
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.util.Optional;
+import jakarta.ws.rs.NotFoundException;
+import jakarta.ws.rs.ProcessingException;
 import org.apache.jena.ontology.ConversionException;
 import org.apache.jena.update.UpdateFactory;
 import org.apache.jena.update.UpdateRequest;
@@ -250,7 +252,18 @@ private com.atomgraph.linkeddatahub.apps.model.Package getPackage(String package
         else
         {
             GraphStoreClient gsc = GraphStoreClient.create(getSystem().getClient(), getSystem().getMediaTypes());
-            model = gsc.getModel(packageURI);
+            try
+            {
+                model = gsc.getModel(packageURI);
+            }
+            catch (NotFoundException ex) // 404 from the package server
+            {
+                return null;
+            }
+            catch (ProcessingException ex) // connection refused, timeout, etc.
+            {
+                return null;
+            }
         }
 
         try