Fix rubocop linting issues in API chat endpoints

- Fix trailing whitespace
- Add missing final newlines
- Fix array bracket spacing
- Auto-corrected all layout issues

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

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

app/views/api/v1/messages/show.json.jbuilder

@@ -13,4 +13,4 @@ json.updated_at @message.updated_at.iso8601
 if @message.type == "UserMessage"
   json.ai_response_status "pending"
   json.ai_response_message "AI response is being generated"
-end
+end