fix: stop portal input capture thread on server exit

Server aborted with "pure virtual method called" when the bind address
was in use: EiScreen's PortalInputCapture glib thread outlived Arch and
hit its freed vtable. ~EiScreen never deleted m_portalInputCapture, and
a fatal startup threw past cleanupServer(). Fix both.

src/lib/deskflow/ServerApp.cpp

@@ -516,7 +516,16 @@ int ServerApp::mainLoop()
   }
 
   // start server, etc
+  try {
     appUtil().startNode();
+  } catch (...) {
+    // a fatal startup failure (e.g. the listen address is already in use)
+    // exits by throwing, which unwinds past the cleanup at the end of this
+    // function. tear the server down here so the screen and its worker
+    // threads don't outlive the app and call into freed globals on exit.
+    cleanupServer();
+    throw;
+  }
 
   // handle hangup signal by reloading the server's configuration
   ARCH->setSignalHandler(Arch::ThreadSignal::Hangup, &reloadSignalHandler, nullptr);

src/lib/platform/EiScreen.cpp

@@ -94,6 +94,7 @@ EiScreen::~EiScreen()
   delete m_clipboard;
 
   delete m_portalRemoteDesktop;
+  delete m_portalInputCapture;
 }
 
 void EiScreen::eiLogEvent(ei_log_priority priority, const char *message) const