Route VR lifecycle through platform services

src/platform_legacy/legacy_platform_services.cpp

@@ -587,6 +587,15 @@ public:
 #endif
     }
 
+    [[nodiscard]] bool start_vr_mode() override
+    {
+        return false;
+    }
+
+    void stop_vr_mode() override
+    {
+    }
+
     void save_prepared_file(
         std::string_view path,
         std::string_view suggested_name,