feat: add subscription and photo sending to bot handler

src/CasaBot/CasaBotApp/BotHandler.cs

@@ -58,7 +58,40 @@ public class BotHandler
             _bot.SendMessage(subscriber, message);
         }
     }
+    
+    public void Subscribe(long id)
+    {
+        if (_subscribers.Any(s => s.Identifier == id))
+        {
+            _logger.LogWarning("User {Id} is already subscribed", id);
+            return;
+        }
 
+        _subscribers.Add(new ChatId(id));
+        _logger.LogInformation("User {Id} subscribed to receive messages", id);
+    }
+    
+    public async Task UpdatePhoto(string path)
+    {
+        if (_bot is null)
+        {
+            _logger.LogWarning("Bot is not initialized yet");
+            return;
+        }
+
+        if (_subscribers.Count == 0)
+        {
+            _logger.LogWarning("No subscribers to send message to");
+            return;
+        }
+
+        foreach (var subscriber in _subscribers)
+        {
+            await using var stream = File.OpenRead(path);
+            var inputFile = InputFile.FromStream(stream, Path.GetFileName(path));
+            await _bot.SendPhoto(subscriber, inputFile, "Detected object");
+        }
+    }
     private async Task SendImageTest(long id)
     {
         if (_bot is null)