Route prepared file targets through platform services

src/platform_legacy/legacy_platform_services.cpp

@@ -431,6 +431,34 @@ public:
 #endif
     }
 
+    [[nodiscard]] pp::platform::PreparedFileTarget prepare_writable_file(
+        std::string_view type,
+        std::string_view default_name,
+        std::string_view data_path,
+        std::string_view temporary_path) override
+    {
+        const std::string name = std::string(default_name) + "." + std::string(type);
+#ifdef __IOS__
+        (void)data_path;
+        return {
+            std::string(temporary_path) + "/" + name,
+            name,
+            true,
+        };
+#elif __WEB__
+        (void)temporary_path;
+        return {
+            std::string(data_path) + "/" + name,
+            name,
+            false,
+        };
+#else
+        (void)data_path;
+        (void)temporary_path;
+        return {};
+#endif
+    }
+
     void display_file(std::string_view path) override
     {
         const std::string value(path);