Fixed bug with Insight QApplication object being created too soon, which in turn caused issues with signal capturing.

Also ensured that we only initialise the Insight object when the user has enabled Insight in their config.

src/Application.hpp

@@ -73,12 +73,19 @@ namespace Bloom
          * Insight is, effectively, a small Qt application that serves a GUI to the user. It occupies the main thread,
          * as well as a single worker thread, and possibly other threads created by Qt.
          *
+         * Insight is optional - users can disable it via their project configuration.
+         *
          * When the user closes the Insight GUI, control of the main thread is returned to Application::run(). How we
          * deal with the GUI being closed at this point depends on user configuration.
          *
          * See the Insight class for more on this.
+         *
+         * Because Insight is optional, we only construct the Insight object when we need it. We can't use
+         * std::optional here because the Insight class extends QObject, which disables the copy constructor and
+         * the assignment operator. So we use an std::unique_ptr instead, which is perfectly fine for this use case,
+         * as we want to manage the lifetime of the object here.
          */
-        Insight insight = Insight(this->eventManager);
+        std::unique_ptr<Insight> insight = nullptr;
 
         /**
          * Configuration extracted from the user's project configuration file.