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

Fix: #31727
After:

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

models/project/project.go

@@ -103,6 +103,13 @@ 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

options/locale/locale_en-US.ini

@@ -3705,6 +3705,7 @@ variables.update.failed = Failed to edit variable.
 variables.update.success = The variable has been edited.
 
 [projects]
+deleted.display_name = Deleted Project
 type-1.display_name = Individual Project
 type-2.display_name = Repository Project
 type-3.display_name = Organization Project

routers/web/repo/issue.go

@@ -1676,7 +1676,7 @@ func ViewIssue(ctx *context.Context) {
 			}
 
 			ghostProject := &project_model.Project{
-				ID:    -1,
+				ID:    project_model.GhostProjectID,
 				Title: ctx.Locale.TrString("repo.issues.deleted_project"),
 			}
 

templates/repo/issue/view_content/comments.tmpl

@@ -581,13 +581,19 @@
 					{{template "shared/user/authorlink" .Poster}}
 					{{$oldProjectDisplayHtml := "Unknown Project"}}
 					{{if .OldProject}}
-						{{$trKey := printf "projects.type-%d.display_name" .OldProject.Type}}
-						{{$oldProjectDisplayHtml = HTMLFormat `<span data-tooltip-content="%s">%s</span>` (ctx.Locale.Tr $trKey) .OldProject.Title}}
+						{{$tooltip := ctx.Locale.Tr "projects.deleted.display_name"}}
+						{{if not .OldProject.IsGhost}}
+							{{$tooltip = ctx.Locale.Tr (printf "projects.type-%d.display_name" .OldProject.Type)}}
+						{{end}}
+						{{$oldProjectDisplayHtml = HTMLFormat `<span data-tooltip-content="%s">%s</span>` $tooltip .OldProject.Title}}
 					{{end}}
 					{{$newProjectDisplayHtml := "Unknown Project"}}
 					{{if .Project}}
-						{{$trKey := printf "projects.type-%d.display_name" .Project.Type}}
-						{{$newProjectDisplayHtml = HTMLFormat `<span data-tooltip-content="%s">%s</span>` (ctx.Locale.Tr $trKey) .Project.Title}}
+						{{$tooltip := ctx.Locale.Tr "projects.deleted.display_name"}}
+						{{if not .Project.IsGhost}}
+							{{$tooltip = ctx.Locale.Tr (printf "projects.type-%d.display_name" .Project.Type)}}
+						{{end}}
+						{{$newProjectDisplayHtml = HTMLFormat `<span data-tooltip-content="%s">%s</span>` $tooltip .Project.Title}}
 					{{end}}
 					{{if and (gt .OldProjectID 0) (gt .ProjectID 0)}}
 						{{ctx.Locale.Tr "repo.issues.change_project_at" $oldProjectDisplayHtml $newProjectDisplayHtml $createdStr}}