Level-Up Rewards & Shop System

🎮 Level-Up Rewards

• Users now automatically receive Coins on Level-Up
• Reward: Level x 100 Coins
• Reward displayed in Level-Up embed

🛒 New Shop System

• Server admins can create a Shop on the homepage
• Items with: Name, description, price, stock, role reward, image
• Users can view the shop with /shop view
• Purchase with /shop buy - coins are deducted
• Roles are automatically assigned (if configured)
• Purchase history visible in admin panel

🔧 Database

• New tables: shop_items, shop_purchases