🐞 Changing terminal font size in settings does not have immediate effect

### Description

Changing terminal font size in settings does not immediately change the terminal font like changing the editor font size does. After restarting CodeEdit the change is correctly honoured.

### To Reproduce

1. Go to Settings->Terminal
2. Disable "Use text editor font"
3. Change font size to 15
4. Close settings.
5. Result: Terminal font stays the same, no change is visible. (Except line height)
6. After restarting CodeEdit, the changed terminal font size is correctly used in the terminal window.

### Expected Behavior

1. Go to Settings->Terminal
2. Disable "Use text editor font"
3. Change font size to 15
4. Terminal font size in terminal window is changed immediately (like changing text editor font size)
5. Close settings.

### Version Information

CodeEdit: CodeEdit: 0.3.6 (47)
macOS: 15.7.1
Xcode: 26.1.1 (17B100)

### Additional Context

_No response_

### Screenshots

首先，在 Settings → Terminal 中停用「Use text editor font」以重現此問題，接著在 Swift 程式碼庫中追蹤終端機設定和字型更新路徑。當變更終端機字型大小後，開啟的終端機無需重新啟動應用程式即可立即更新時，這項工作就完成了。

由索引模型根據 Issue 內容生成。