feat: Add example video to README.md and include video tag

Author: skhelladi

README.md

@@ -4,6 +4,12 @@
 
 Based on [FTXUI](https://github.com/ArthurSonzogni/FTXUI), TUIKit is a modern C++ framework designed to build rich and interactive Terminal User Interfaces (TUIs). Inspired by the simplicity and power of the Qt framework, TUIKit aims to provide a familiar development experience for creating command-line applications, especially suited for scientific and engineering projects.
 
+<video width="640" height="480" controls>
+  <source src="docs/example_1.mp4" type="video/mp4">
+  Your browser does not support the video tag.
+</video>
+
+
 ## 🧩 Core Principles (Qt-like Philosophy)
 
 *   **Hierarchical Widgets:** Utilize a structured hierarchy of UI components (`TUIWidget`, `TUIForm`, `TUIMenu`, etc.).