Route prepared file targets through platform services

src/app.h

@@ -181,12 +181,9 @@ public:
     bool clipboard_set_text(const std::string& s);
     void pick_image(std::function<void(std::string path)> callback);
     void pick_file(std::vector<std::string> types, std::function<void(std::string path)> callback);
-#if __IOS__ || __WEB__
     void pick_file_save(const std::string& type, const std::string& default_name,
         std::function<void(std::string path)> writer, std::function<void(const std::string& path, bool saved)> callback);
-#else
     void pick_file_save(std::vector<std::string> types, std::function<void(std::string path)> callback);
-#endif
     void pick_dir(std::function<void(std::string path)> callback);
     void display_file(std::string path);
     void share_file(std::string path);