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/ball.lua

@@ -0,0 +1,81 @@
+-- NAME: Bouncing Ball
+-- DESC: Physics demo with state management
+
+-- States
+local STATE_PAUSED = 0
+local STATE_RUNNING = 1
+
+function init()
+    game.vars.state = STATE_PAUSED
+    game.vars.ball_x = game.width() / 2
+    game.vars.ball_y = game.height() / 2
+    game.vars.vel_x = 3
+    game.vars.vel_y = 2
+    game.vars.radius = 10
+    game.vars.frame_count = 0
+    
+    print("Bouncing Ball initialized")
+end
+
+function update(event)
+    -- Toggle pause on tap
+    if event.type == INPUT.TOUCH_DOWN or event.type == INPUT.BUTTON_0 or event.type == INPUT.BUTTON_1 then
+        if game.vars.state == STATE_PAUSED then
+            game.vars.state = STATE_RUNNING
+        else
+            game.vars.state = STATE_PAUSED
+        end
+        return true
+    end
+    
+    -- Update physics if running
+    if game.vars.state == STATE_RUNNING then
+        -- Move ball
+        game.vars.ball_x = game.vars.ball_x + game.vars.vel_x
+        game.vars.ball_y = game.vars.ball_y + game.vars.vel_y
+        
+        -- Bounce off walls
+        if game.vars.ball_x - game.vars.radius < 0 or game.vars.ball_x + game.vars.radius > game.width() then
+            game.vars.vel_x = -game.vars.vel_x
+            game.vars.ball_x = math.max(game.vars.radius, math.min(game.width() - game.vars.radius, game.vars.ball_x))
+        end
+        
+        if game.vars.ball_y - game.vars.radius < 0 or game.vars.ball_y + game.vars.radius > game.height() then
+            game.vars.vel_y = -game.vars.vel_y
+            game.vars.ball_y = math.max(game.vars.radius, math.min(game.height() - game.vars.radius, game.vars.ball_y))
+        end
+        
+        game.vars.frame_count = game.vars.frame_count + 1
+        return true  -- Always redraw when running
+    end
+    
+    return false
+end
+
+function draw()
+    renderer.clear(false)
+    
+    -- Draw ball
+    renderer.circle(game.vars.ball_x, game.vars.ball_y, game.vars.radius, true, true)
+    
+    -- Draw trail (previous positions)
+    local trail_radius = game.vars.radius - 2
+    if trail_radius > 2 then
+        renderer.circle(game.vars.ball_x - game.vars.vel_x, 
+                       game.vars.ball_y - game.vars.vel_y, 
+                       trail_radius, true, false)
+    end
+    
+    -- Draw status
+    if game.vars.state == STATE_PAUSED then
+        renderer.text(10, 10, "PAUSED - Tap to start", true)
+    else
+        renderer.text(10, 10, "Frames: " .. tostring(game.vars.frame_count), true)
+        renderer.text(10, 25, "Tap to pause", true)
+    end
+    
+    -- Draw velocity vector
+    local arrow_x = game.vars.ball_x + game.vars.vel_x * 3
+    local arrow_y = game.vars.ball_y + game.vars.vel_y * 3
+    renderer.line(game.vars.ball_x, game.vars.ball_y, arrow_x, arrow_y, true, 2)
+end