test: add JUnit 5 + surefire harness

Emulator/pom.xml

@@ -62,6 +62,12 @@
                     <show>public</show>
                 </configuration>
             </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.2.5</version>
+            </plugin>
         </plugins>
     </build>
 
@@ -172,12 +178,20 @@
             <version>0.4</version>
         </dependency>
 
-        <!-- Jakarta Mail � used by the built-in forgot-password endpoint
+        <!-- Jakarta Mail — used by the built-in forgot-password endpoint
              when smtp.* keys are configured in emulator_settings -->
         <dependency>
             <groupId>org.eclipse.angus</groupId>
             <artifactId>jakarta.mail</artifactId>
             <version>2.0.3</version>
         </dependency>
+
+        <!-- JUnit Jupiter -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.10.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>