Use DATA_NAME for Qt applicationName on Linux

Consolidates APP_NAME into DATA_NAME and removes redundant MainName().
Ensures Qt's QStandardPaths (cache, config dirs) match our Paths code,
fixing duplicate cache directories on Linux.

CMakeModules/NameConfiguration.cmake

@@ -1,10 +1,10 @@
 set(MAIN_TARGET JellyfinDesktop)
 
-# Display name (window title, application name)
-set(DISPLAY_NAME "Jellyfin Desktop")
-
-# Name of the output binary and data directories
+# Output binary name
 set(MAIN_NAME jellyfin-desktop)
+
+# Data directory name - also used for QCoreApplication::applicationName
+# which determines QStandardPaths (cache, config, data dirs)
 set(DATA_NAME jellyfin-desktop)
 
 if(APPLE)

src/main.cpp

@@ -93,7 +93,7 @@ static void setupMpvFallback()
 /////////////////////////////////////////////////////////////////////////////////////////
 static void preinitQt()
 {
-  QCoreApplication::setApplicationName(Names::MainName());
+  QCoreApplication::setApplicationName(Names::DataName());
   QCoreApplication::setApplicationVersion(Version::GetVersionString());
   QCoreApplication::setOrganizationDomain("jellyfin.org");
 

src/shared/Names.cpp.in

@@ -4,11 +4,6 @@
 
 #include "Names.h"
 
-QString Names::MainName()
-{
-  return QString("@DISPLAY_NAME@");
-}
-
 QString Names::DataName()
 {
   return QString("@DATA_NAME@");

src/shared/Names.h

@@ -9,7 +9,6 @@
 
 namespace Names
 {
-  QString MainName();
   QString DataName();
   QString HelperName();
 };