Differentiate placeholder reason from inputted reason for missed HM

In the missed house meetings table on the dashboard, it displays the date of missed HM, as well as a reason. It should be easy to tell whether the displayed reason is a user inputted reason, or if it is displaying the default value bc no reason was provided

This could be done by making the style different, or by changing the text to something that says that no reason was provided

先找出負責呈現錯過的 house meetings 表格的 dashboard 元件，並檢查其 reason 值是如何顯示的。透過樣式或文字，讓預設的無 reason 值能與使用者輸入的 reason 區分開來，然後確認表格是否清楚傳達目前顯示的是哪一種 reason。

由索引模型根據 Issue 內容生成。