Add opt-in piped input support for POSIX systems

Enables applications to read piped data while maintaining interactive
keyboard input by redirecting stdin to /dev/tty when explicitly enabled.

README.md

@@ -378,6 +378,22 @@ Several games using the FTXUI have been made during the Game Jam:
 - [smoothlife](https://github.com/cpp-best-practices/game_jam/blob/main/Jam1_April_2022/smoothlife.md)
 - [Consu](https://github.com/cpp-best-practices/game_jam/blob/main/Jam1_April_2022/consu.md)
 
+## Advanced Usage
+
+### Piped Input Support
+
+If your application reads from stdin (piped data) and also needs interactive keyboard input:
+
+```cpp
+auto screen = ScreenInteractive::Fullscreen();
+screen.HandlePipedInput(true);  // Enable before Loop()
+screen.Loop(component);
+```
+
+This allows commands like `cat data.txt | your_app` to work with full keyboard interaction.
+
+**Note:** This feature is only available on POSIX systems (Linux/macOS). On Windows, the method call is a no-op.
+
 ## Build using CMake
 
 It is **highly** recommended to use CMake FetchContent to depend on FTXUI so you may specify which commit you would like to depend on.