fix: cleanly exit on shutdown (#5537)

Co-authored-by: Mm2PL <mm2pl+gh@kotmisia.pl>
Co-authored-by: Nerixyz <nerixdev@outlook.de>

src/singletons/StreamerMode.hpp

@@ -20,6 +20,8 @@ public:
 
     [[nodiscard]] virtual bool isEnabled() const = 0;
 
+    virtual void start() = 0;
+
 signals:
     void changed(bool enabled);
 };
@@ -37,6 +39,8 @@ public:
 
     bool isEnabled() const override;
 
+    void start() override;
+
 private:
     void updated(bool enabled);