build: add Maven wrapper and prebuilt release jar; ignore docs/superpowers

- Add ./mvnw wrapper (script-only) so the project builds/runs without a
  system Maven install.
- Add maven-shade-plugin producing a self-contained release/HauntedManor.jar
  (merges audio SPI services; no dependency-reduced-pom).
- Document running via ./mvnw and via the jar directly in the README.
- Ignore docs/superpowers/ (planning specs kept locally, untracked).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Semesterprojekt/pom.xml

@@ -109,6 +109,36 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>3.5.2</version>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <version>3.6.0</version>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                        <configuration>
+                            <!-- Self-contained, runnable JAR with all dependencies bundled. -->
+                            <outputFile>${project.basedir}/release/HauntedManor.jar</outputFile>
+                            <createDependencyReducedPom>false</createDependencyReducedPom>
+                            <transformers>
+                                <!-- Default entry point: console version. GUI via -cp ... AppGui. -->
+                                <transformer
+                                        implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+                                    <manifestEntries>
+                                        <Main-Class>thb.jeanluc.adventure.App</Main-Class>
+                                    </manifestEntries>
+                                </transformer>
+                                <!-- Merge META-INF/services so the OGG Vorbis SPI keeps working. -->
+                                <transformer
+                                        implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
+                            </transformers>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>exec-maven-plugin</artifactId>