Basic shell working.

Frontend.h

@@ -0,0 +1,27 @@
+/*
+ * Frontend.h - top-level container that couples Input + Renderer and runs the loop
+ */
+#ifndef KTE_FRONTEND_H
+#define KTE_FRONTEND_H
+
+#include <memory>
+
+class Editor;
+class InputHandler;
+class Renderer;
+
+class Frontend {
+public:
+    virtual ~Frontend() = default;
+
+    // Initialize the frontend (create window/terminal, etc.)
+    virtual bool Init(Editor &ed) = 0;
+
+    // Execute one iteration (poll input, dispatch, draw). Set running=false to exit.
+    virtual void Step(Editor &ed, bool &running) = 0;
+
+    // Shutdown/cleanup
+    virtual void Shutdown() = 0;
+};
+
+#endif // KTE_FRONTEND_H