# Task ID: 16
# Title: Game End & Settlement System
# Status: pending
# Dependencies: 5, 15
# Priority: high
# Description: Implement the logic and UI for ending a game, determining the winner, and displaying a settlement screen with results and rewards (e.g., experience points).
# Details:
Backend: When a win condition is met, update player stats (wins, losses, streaks, experience) in MongoDB. Calculate XP based on victory/defeat (win +100XP, loss +20XP). Frontend: Display a 'Game Over' modal/screen showing winner/loser, final board state, and earned XP/rewards. Include 'Play Again' and 'Return to Lobby' buttons.

# Test Strategy:
Play games to completion (win/loss) and verify correct winner determination. Check if XP and stats are updated in the database. Verify settlement screen displays accurate information. Test 'Play Again' and 'Return to Lobby' functionality.