Difficulty Selector, Rebalance & Captured Pieces Display — Chesscent Steam update #5720530

Global Difficulty Selector: You can now choose between Easy, Normal, and Hard in the Settings menu. This setting dynamically modifies the base challenge of each stage, letting you tailor the gameplay experience to your preference. Standard Balance Tweaks: Recalibrated the AI engine's baseline parameters on Normal difficulty for a smoother, better-balanced progression across all worlds. Captured Pieces Display: Added an in-game panel showing captured pieces for both sides in real time