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_launcher.cpp

@@ -16,7 +16,7 @@ GameLauncher::GameLauncher(uint16_t width, uint16_t height,
 }
 
 void GameLauncher::register_game(const char* name, const char* description,
-                                 Game* (*factory)(uint16_t, uint16_t, LowLevelRenderer*, LowLevelGUI*, InputManager*)) {
+                                 std::function<Game*(uint16_t, uint16_t, LowLevelRenderer*, LowLevelGUI*, InputManager*)> factory) {
     GameEntry entry;
     entry.name = name;
     entry.description = description;