Plan out further migration steps

backend/src/api/handler.rs

@@ -505,6 +505,15 @@ impl ApiMessageHandler {
                 false
             }
             ApiMessage::LoadSettings(id, name, variant_id, variant_name) => {
+                /* Migration steps:
+                1. Modify to the frontend to send the game ID in this message (`id` here is the app
+                   ID).
+                2. Change game ID to app ID.
+                3. (Create and) call function to merge OldSettingsJson with existing FileJson, or
+                   use existing `From<OldSettingsJson> for FileJson` if this game doesn't have a
+                   save in the new format yet.
+                4. Let the rest of the code below work its magic.
+                */
                 let path = format!("{}.ron", id);
                 if let Err(e) = settings.on_unload() {
                     print_errors("LoadSettings on_unload()", e);