Add: Debug logging for product variant data in TeleBot

Log variant count and prices when fetching products to diagnose
why variants aren't being detected during add-to-cart flow.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

TeleBot/TeleBot/Services/LittleShopService.cs

@@ -141,11 +141,18 @@ namespace TeleBot.Services
             {
                 if (!await AuthenticateAsync())
                     return null;
-                
+
                 var result = await _client.Catalog.GetProductByIdAsync(productId);
-                
+
                 if (result.IsSuccess && result.Data != null && result.Data.IsActive)
                 {
+                    _logger.LogInformation("GetProduct {ProductId}: {Name} | Variants: {Count} | Base Price: £{Price}",
+                        productId, result.Data.Name, result.Data.Variants?.Count ?? 0, result.Data.Price);
+                    if (result.Data.Variants?.Any() == true)
+                    {
+                        _logger.LogInformation("  First variant: {Name} at £{Price}",
+                            result.Data.Variants.First().Name, result.Data.Variants.First().Price);
+                    }
                     return result.Data;
                 }