test(Resources): Add comprehensive resource system tests (8 new test files, +48 test cases)

- Add Shader tests (8 test cases)
- Add Material tests (13 test cases)
- Add FileArchive tests (7 test cases)
- Add Loader tests for Texture, Mesh, Audio, Shader, Material (4 tests each)
- Implement IResourceLoader.cpp with ReadFileData and GetExtension
- Update CMakeLists.txt to include new test files and source

tests/Resources/test_texture_loader.cpp

@@ -0,0 +1,37 @@
+#include <gtest/gtest.h>
+#include <XCEngine/Resources/TextureLoader.h>
+#include <XCEngine/Resources/ResourceTypes.h>
+#include <XCEngine/Containers/Array.h>
+
+using namespace XCEngine::Resources;
+using namespace XCEngine::Containers;
+
+namespace {
+
+TEST(TextureLoader, GetResourceType) {
+    TextureLoader loader;
+    EXPECT_EQ(loader.GetResourceType(), ResourceType::Texture);
+}
+
+TEST(TextureLoader, GetSupportedExtensions) {
+    TextureLoader loader;
+    auto extensions = loader.GetSupportedExtensions();
+    EXPECT_GE(extensions.Size(), 1u);
+}
+
+TEST(TextureLoader, CanLoad) {
+    TextureLoader loader;
+    EXPECT_TRUE(loader.CanLoad("test.png"));
+    EXPECT_TRUE(loader.CanLoad("test.jpg"));
+    EXPECT_TRUE(loader.CanLoad("test.tga"));
+    EXPECT_FALSE(loader.CanLoad("test.txt"));
+    EXPECT_FALSE(loader.CanLoad("test.obj"));
+}
+
+TEST(TextureLoader, LoadInvalidPath) {
+    TextureLoader loader;
+    LoadResult result = loader.Load("invalid/path/texture.png");
+    EXPECT_FALSE(result);
+}
+
+} // namespace