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_examples/counter.lua

@@ -0,0 +1,49 @@
+-- NAME: Touch Counter
+-- DESC: Simple tap counter demo
+
+-- Initialize game state
+function init()
+    game.vars.count = 0
+    game.vars.last_x = 0
+    game.vars.last_y = 0
+    print("Counter initialized")
+end
+
+-- Update game logic based on input
+function update(event)
+    -- Check if touch/button pressed
+    if event.type == INPUT.TOUCH_DOWN or event.type == INPUT.BUTTON_0 or event.type == INPUT.BUTTON_1 then
+        game.vars.count = game.vars.count + 1
+        game.vars.last_x = event.x
+        game.vars.last_y = event.y
+        print("Count: " .. game.vars.count)
+        return true  -- Request redraw
+    end
+    
+    return false  -- No redraw needed
+end
+
+-- Draw the game
+function draw()
+    -- Clear screen
+    renderer.clear(true)
+    
+    -- Draw title
+    renderer.text(20, 20, "Touch Counter", true)
+    
+    -- Draw count (centered)
+    local count_text = "Count: " .. tostring(game.vars.count)
+    renderer.text(game.width() / 2 - 40, game.height() / 2 - 10, count_text, true)
+    
+    -- Draw last touch position
+    if game.vars.count > 0 then
+        local pos_text = "Last: (" .. tostring(game.vars.last_x) .. ", " .. tostring(game.vars.last_y) .. ")"
+        renderer.text(20, game.height() - 30, pos_text, true)
+        
+        -- Draw marker at last touch
+        renderer.circle(game.vars.last_x, game.vars.last_y, 5, true, false)
+    end
+    
+    -- Draw instructions
+    renderer.text(20, 50, "Tap screen to increment", true)
+end