fix: Update system reboot handling and refactor service constants

- Changed the reboot command in ImageWriter to suppress unused return value.
- Refactored service and path constants in GnomeSuspendInhibitor to use const char* for better compatibility.
- Initialized QDBusConnection in GnomeSuspendInhibitor directly during declaration.

Author: tdewey-rpi

src/imagewriter.cpp

@@ -2533,7 +2533,7 @@ void MountUtilsLog(std::string msg) {
 void ImageWriter::reboot()
 {
     qDebug() << "Rebooting system.";
-    system("reboot");
+    (void)system("reboot");
 }
 
 void ImageWriter::openUrl(const QUrl &url)

src/linux/linux_suspend_inhibitor.cpp

@@ -12,8 +12,8 @@
 #include <QtDBus/QtDBus>
 
 namespace {
-    constexpr QString service = "org.gnome.SessionManager";
-    constexpr QString path = "/org/gnome/SessionManager";
+    constexpr const char* service = "org.gnome.SessionManager";
+    constexpr const char* path = "/org/gnome/SessionManager";
 }
 
 GnomeSuspendInhibitor::GnomeSuspendInhibitor()

src/linux/linux_suspend_inhibitor.h

@@ -7,7 +7,7 @@
 
 class GnomeSuspendInhibitor
 {
-    QDBusConnection _bus;
+    QDBusConnection _bus = QDBusConnection::sessionBus();
     bool _serviceFound;
     int _cookie;
 public: