Achievements + Menu Polish

Achievements Added

• Complete your first puzzle

• Complete 10 puzzles

• Complete 20 puzzles

• Complete all 40 puzzles

• Complete a puzzle on each difficulty (Easy, Medium, Hard)

• Complete a custom puzzle using your own image

Menu Improvements

• Added rotating character art on the main menu: cycles through different character images with a "slide-in" and "slide-out" animation every 10 seconds. It's a small touch, but it makes things feel more alive.

Thanks for playing; enjoy!