Fix playback, API races, tray, MPRIS, and search UX; add tests

- Correct history/resume next-previous context and list index resync after reload
- Abort stale RadioBrowser requests and suppress error banners when cache satisfies loads
- Reset local search filter on page changes and debounce compact-mode API search
- Move system tray to C++ (QSystemTrayIcon) for reliable Wayland context menus
- Harden MPRIS registration and metadata updates for Plasma media widgets
- Add playback and API race unit tests
- Drop unused KF6 Kirigami, I18n, and CoreAddons build dependencies
- Update packaging docs, CI, and PKGBUILD to match Qt-only requirements

translations/bearwave_de.ts

@@ -279,6 +279,33 @@
       <translation>Zuletzt gehört</translation>
     </message>
   </context>
+  <context>
+    <name>SystemTrayManager</name>
+    <message>
+      <source>BearWave</source>
+      <translation>BearWave</translation>
+    </message>
+    <message>
+      <source>Pause</source>
+      <translation>Pause</translation>
+    </message>
+    <message>
+      <source>Play</source>
+      <translation>Wiedergabe</translation>
+    </message>
+    <message>
+      <source>Hide</source>
+      <translation>Verstecken</translation>
+    </message>
+    <message>
+      <source>Show</source>
+      <translation>Zeigen</translation>
+    </message>
+    <message>
+      <source>Quit</source>
+      <translation>Beenden</translation>
+    </message>
+  </context>
   <context>
     <name>RadioBrowser</name>
     <message>