Add Lua 5.4 scripting integration for dynamic game loading

- Integrated Lua 5.4 engine (32-bit mode for embedded ARM)
- Created LuaGame wrapper class implementing Game interface
- Added C++ bindings exposing renderer, game state, and input to Lua
- Implemented SD card loader for automatic .lua game discovery
- Updated GameLauncher to support std::function for lambda captures
- Made Game class members public for Lua bindings access
- Added example Lua games: counter, snake, bouncing ball
- Included comprehensive API documentation

Games can now be written as .lua text files on SD card and loaded
without recompilation. Build size: 747KB UF2, Lua VM uses ~50-80KB RAM.

lib/game.h

@@ -99,12 +99,11 @@ public:
      */
     virtual Type get_type() const { return Type::BASE; }
 
-protected:
-    // Display dimensions
+    // Display dimensions (public for Lua bindings)
     uint16_t width;
     uint16_t height;
     
-    // Rendering interfaces (provided by basic1.cpp)
+    // Rendering interfaces (provided by basic1.cpp, public for Lua bindings)
     LowLevelRenderer* renderer;
     LowLevelGUI* gui;