docs: update TEST_SPEC.md and README.md to reflect new directory structure

- TEST_SPEC.md: Updated test directory structure to reflect Core/Asset,
  Core/IO, and Resources/<Type> subdirectories
- TEST_SPEC.md: Updated module names and test counts (852 total)
- TEST_SPEC.md: Updated build commands for new Resources subdirectories
- README.md: Updated engine structure with Core/Asset/ and Core/IO/
- README.md: Updated Resources section with layered architecture
- README.md: Updated test coverage table with accurate counts

tests/Core/IO/test_iresource_loader.cpp

@@ -0,0 +1,39 @@
+#include <gtest/gtest.h>
+#include <XCEngine/Core/IO/IResourceLoader.h>
+#include <XCEngine/Core/Asset/ResourceTypes.h>
+#include <XCEngine/Core/Asset/ResourceManager.h>
+#include <XCEngine/Core/Containers/String.h>
+
+using namespace XCEngine::Resources;
+using namespace XCEngine::Containers;
+
+namespace {
+
+TEST(LoadResult, DefaultConstructor) {
+    LoadResult result;
+    EXPECT_FALSE(result.success);
+    EXPECT_EQ(result.resource, nullptr);
+    EXPECT_FALSE(result);
+}
+
+TEST(LoadResult, FromBool) {
+    LoadResult result(true);
+    EXPECT_TRUE(result.success);
+}
+
+TEST(LoadResult, FromErrorString) {
+    XCEngine::Containers::String errorMsg = "Error loading file";
+    LoadResult result(errorMsg);
+    EXPECT_FALSE(result.success);
+    EXPECT_STREQ(result.errorMessage.CStr(), "Error loading file");
+}
+
+TEST(LoadResult, BoolOperator) {
+    LoadResult emptyResult;
+    EXPECT_FALSE(emptyResult);
+    
+    LoadResult errorResult("error");
+    EXPECT_FALSE(errorResult);
+}
+
+} // namespace