Fix: Prevent 'message not modified' error when browsing products

**Issue**: When users clicked "Browse Products" multiple times, Telegram API
rejected the edit request with "message is not modified" error, causing the
browse functionality to appear broken.

**Root Cause**: HandleBrowse method used EditMessageTextAsync directly, which
throws an exception when the message content is identical.

**Solution**:
- Replaced direct EditMessageTextAsync with SafeEditMessageAsync
- SafeEditMessageAsync catches ApiRequestException for "message is not modified"
- Silently handles duplicate edits without user-facing errors

**Testing**:
- Deployed to production (container: e1467c559ff6)
- Bot running as @Slukdevukbot with TOR enabled
- Categories API confirmed working (3 categories, 10 products)

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

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

TeleBot/TeleBot/Handlers/CallbackHandler.cs

@@ -243,13 +243,14 @@ namespace TeleBot.Handlers
             );
 
             var categories = await _shopService.GetCategoriesAsync();
-            
-            await bot.EditMessageTextAsync(
+
+            await SafeEditMessageAsync(
+                bot,
                 message.Chat.Id,
                 message.MessageId,
                 MessageFormatter.FormatCategories(categories),
-                parseMode: Telegram.Bot.Types.Enums.ParseMode.Markdown,
-                replyMarkup: MenuBuilder.CategoryMenu(categories)
+                Telegram.Bot.Types.Enums.ParseMode.Markdown,
+                MenuBuilder.CategoryMenu(categories)
             );
             session.State = SessionState.BrowsingCategories;
         }