Fix the display of project type for deleted projects (#31732) (#31734)

Backport #31732 by @yp05327

Fix: #31727
After:

![image](https://github.com/user-attachments/assets/1dfb4b31-3bd6-47f7-b126-650f33f453e2)

Co-authored-by: yp05327 <576951401@qq.com>

models/project/project.go

@@ -109,6 +109,13 @@ type Project struct {
 	ClosedDateUnix timeutil.TimeStamp
 }
 
+// Ghost Project is a project which has been deleted
+const GhostProjectID = -1
+
+func (p *Project) IsGhost() bool {
+	return p.ID == GhostProjectID
+}
+
 func (p *Project) LoadOwner(ctx context.Context) (err error) {
 	if p.Owner != nil {
 		return nil