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.

games/lua_bindings.h

@@ -0,0 +1,23 @@
+// ============================================================================
+// LUA BINDINGS - HEADER
+// ============================================================================
+// Exposes C++ game API to Lua scripts
+
+#ifndef LUA_BINDINGS_H
+#define LUA_BINDINGS_H
+
+extern "C" {
+    #include "lua.h"
+}
+
+// Forward declaration
+class LuaGame;
+
+/**
+ * @brief Register all game API functions with Lua state
+ * @param L Lua state
+ * @param game Pointer to LuaGame instance (stored as light userdata)
+ */
+void lua_bindings_register(lua_State* L, LuaGame* game);
+
+#endif // LUA_BINDINGS_H