add button for opening mod folder

launcherbackend.cpp

@@ -1,11 +1,13 @@
 #include "launcherbackend.h"
 
+#include <QDesktopServices>
 #include <QDir>
 #include <QFile>
 #include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
 #include <QStandardPaths>
+#include <QUrl>
 #include <algorithm>
 
 LauncherBackend::LauncherBackend(QObject *parent)
@@ -117,6 +119,26 @@ void LauncherBackend::launchGame(int profileIndex, int versionIndex)
     emit launched(profile.name, version.name, version.serverUrl);
 }
 
+QString LauncherBackend::minecraftDir() const
+{
+#if defined(Q_OS_WIN)
+    return QDir::homePath() + "/AppData/Roaming/.minecraft";
+#elif defined(Q_OS_MACOS)
+    return QDir::homePath() + "/Library/Application Support/minecraft";
+#else // Linux и прочие Unix-системы
+    return QDir::homePath() + "/.minecraft";
+#endif
+}
+
+void LauncherBackend::openMinecraftFolder()
+{
+    const QString modsDir = minecraftDir() + "/mods";
+    QDir().mkpath(modsDir);
+
+    if (!QDesktopServices::openUrl(QUrl::fromLocalFile(modsDir)))
+        emit launchError("Не удалось открыть папку с модами");
+}
+
 void LauncherBackend::loadData()
 {
     auto loadFile = [](const QString &path, auto handler) {