feat: Update UI for Copilot (#11561)

- Updated UI for copilot

enterprise/app/helpers/captain/chat_helper.rb

@@ -53,9 +53,21 @@ module Captain::ChatHelper
   end
 
   def execute_tool(function_name, arguments, tool_call_id)
-    persist_message({ content: "Using tool #{function_name}", function_name: function_name }, 'assistant_thinking')
+    persist_message(
+      {
+        content: I18n.t('captain.copilot.using_tool', function_name: function_name),
+        function_name: function_name
+      },
+      'assistant_thinking'
+    )
     result = @tool_registry.send(function_name, arguments)
-    persist_message({ content: "Completed #{function_name} tool call", function_name: function_name }, 'assistant_thinking')
+    persist_message(
+      {
+        content: I18n.t('captain.copilot.completed_tool_call', function_name: function_name),
+        function_name: function_name
+      },
+      'assistant_thinking'
+    )
     append_tool_response(result, tool_call_id)
   end
 
@@ -67,8 +79,8 @@ module Captain::ChatHelper
   end
 
   def process_invalid_tool_call(function_name, tool_call_id)
-    persist_message({ content: 'Invalid tool call', function_name: function_name }, 'assistant_thinking')
-    append_tool_response('Tool not available', tool_call_id)
+    persist_message({ content: I18n.t('captain.copilot.invalid_tool_call'), function_name: function_name }, 'assistant_thinking')
+    append_tool_response(I18n.t('captain.copilot.tool_not_available'), tool_call_id)
   end
 
   def append_tool_response(content, tool_call_id)