Split asset reload platform policy

src/platform_api/asset_file_load_policy.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include "platform_api/platform_policy.h"
+
 #include <cstdint>
 #include <string_view>
 
@@ -11,6 +13,23 @@ struct AssetFileLoadDecision {
     std::int64_t last_write_time = 0;
 };
 
+struct AssetFileTimestampProbe {
+    bool file_exists = false;
+    std::int64_t last_write_time = 0;
+};
+
+[[nodiscard]] AssetFileLoadDecision plan_asset_file_load_with_probe(
+    PlatformFamily family,
+    bool already_loaded,
+    std::int64_t previous_last_write_time,
+    AssetFileTimestampProbe probe) noexcept;
+
+[[nodiscard]] AssetFileLoadDecision plan_asset_file_load_for_platform(
+    PlatformFamily family,
+    std::string_view absolute_path,
+    bool already_loaded,
+    std::int64_t previous_last_write_time);
+
 [[nodiscard]] AssetFileLoadDecision plan_asset_file_load(
     std::string_view absolute_path,
     bool already_loaded,