Centralize legacy preference storage

src/legacy_app_startup_services.cpp

@@ -3,9 +3,8 @@
 #include "legacy_app_startup_services.h"
 
 #include "app.h"
+#include "legacy_preference_storage.h"
 #include "renderer_gl/opengl_capabilities.h"
-#include "serializer.h"
-#include "settings.h"
 
 namespace pp::panopainter {
 namespace {
@@ -21,13 +20,13 @@ public:
 
     void store_run_counter(int value) override
     {
-        Settings::set("run_counter", Serializer::Integer(value));
+        set_legacy_integer_preference("run_counter", value);
         LOG("run_counter %d", value);
     }
 
     void save_preferences() override
     {
-        if (!Settings::save())
+        if (!save_legacy_preferences())
             LOG("save preferences failed");
     }