fix: fix "zh-hans" is not a valid locale error

Author: ramsayleung

app/models/trained_message.rb

@@ -29,7 +29,6 @@ module TrainingTarget
   # Automatically train classifier after creating/updating a message
   after_create :retrain_classifier, if: :trainable?
   after_update :retrain_classifier, if: :trainable_type_changed?
-  after_destroy :retrain_classifier, if: :trainable?
   after_create :should_ban_user, if: :trainable?
   after_update :should_ban_user, if: :trainable_type_changed?
 

app/services/telegram_botter.rb

@@ -47,7 +47,7 @@ def handle_message(bot, message)
 
     # Clean the message text and handle @botname mentions
     message_text = message.text&.strip || ""
-    @lang_code = message.from.language_code || "en"
+    @lang_code = (message.from.language_code || "en").split("-").first
     # Remove @botname from the beginning if present
     message_text = message_text.gsub(/^@#{@bot_username}\s+/, "") if @bot_username