Add a PipeWire audio backend and stereo capture/playback

Capture and playback now go through AudioCapture/AudioPlayback interfaces
with two implementations: PipeWire, used for the system default and for
every pw: device when a session is reachable, and Java Sound for the raw
ALSA devices and other platforms. The PipeWire binding is FFM-based
(PipeWireLibrary, PipeWireSession, PipeWireStream, SpaPod) and enumerates
the graph's real devices, so each stream shows up separately in volume
mixers.

Lines are opened with a negotiated channel count instead of a fixed mono
format: OPUS_MUSIC transmits the stereo capture as-is, OPUS_VOICE keeps
transmitting the mono downmix so the pre-processing chain and VAD still
see a single channel. Java Sound enumeration asks only for "a mixer that
can capture/play" so the PipeWire and PulseAudio ALSA plugins are no
longer hidden by their narrow format lists.

The Java Sound classes are renamed to Desktop* to match what they now
are, and JUnit plus a SpaPod round-trip test are wired into the build.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ts3-client/pom.xml

@@ -22,8 +22,21 @@
         <maven.compiler.release>26</maven.compiler.release>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <ts3j.version>1.0.3</ts3j.version>
+        <surefire.version>3.5.6</surefire.version>
     </properties>
 
+    <build>
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-surefire-plugin</artifactId>
+                    <version>${surefire.version}</version>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+
     <dependencyManagement>
         <dependencies>
             <dependency>