Fix Lua game float-to-int conversion errors for renderer.circle()

All games had the same issue: renderer.circle() requires integer arguments,
but float calculations produced non-integer coordinates.

Fixed in all games using math.floor(x + 0.5) for proper rounding:
- pong.lua: Ball position
- air_hockey.lua: Puck position
- asteroids.lua: Asteroid positions
- ball.lua: Ball and trail positions, velocity line
- breakout.lua: Ball position
- flappy_bird.lua: Bird Y position
- counter.lua: Last touch marker position
- snake.lua: Food position (center calculation)
- tic_tac_toe.lua: O circle center position

Also fixed floating-point coordinate calculations in ball and line
drawing to ensure all coordinates are integers.

games/lua_examples/tic_tac_toe.lua

@@ -127,8 +127,8 @@ function draw()
                     renderer.line(cell_x + 2, cell_y + 2, cell_x + CELL_SIZE - 2, cell_y + CELL_SIZE - 2, true, 1)
                     renderer.line(cell_x + CELL_SIZE - 2, cell_y + 2, cell_x + 2, cell_y + CELL_SIZE - 2, true, 1)
                 elseif value == 2 then
-                    -- Draw O
-                    renderer.circle(cell_x + CELL_SIZE / 2, cell_y + CELL_SIZE / 2, CELL_SIZE / 2 - 2, true, false)
+                    -- Draw O (convert center to integers)
+                    renderer.circle(math.floor(cell_x + CELL_SIZE / 2 + 0.5), math.floor(cell_y + CELL_SIZE / 2 + 0.5), CELL_SIZE / 2 - 2, true, false)
                 end
             end
         end