feat: add OpenGL abstraction layer with RAII resources

- Replace window class with cbt::opengl::context
- Add buffer resource (VBO, EBO, UBO, SSBO) with move semantics
- Add texture resource with format/type enums and filtering
- Add descriptor_set for Vulkan-style resource binding
- All resources use RAII with proper cleanup

cbt/opengl/context.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <string>
+
+#define GLFW_INCLUDE_NONE
+#include "GLFW/glfw3.h"
+
+namespace cbt::opengl {
+
+class context {
+    GLFWwindow* m_window = nullptr;
+    bool m_initialized = false;
+
+    static auto init() -> bool;
+    static auto terminate() -> void;
+    static auto setup_gl() -> bool;
+    static auto print_info() -> void;
+
+public:
+    explicit context(std::string title, int width, int height);
+    ~context();
+
+    auto should_close() const -> bool;
+    auto valid() const -> bool;
+    auto swap_buffers() -> void;
+    auto poll_events() -> void;
+    auto raw() const -> GLFWwindow*;
+};
+
+}