Fix empty git repo handling logic and fix mobile view (#33101) (#33102)

Backport #33101 and UI fix from main (including #33108)

models/repo/repo.go

@@ -276,6 +276,8 @@ func (repo *Repository) IsBroken() bool {
 }
 
 // MarkAsBrokenEmpty marks the repo as broken and empty
+// FIXME: the status "broken" and "is_empty" were abused,
+// The code always set them together, no way to distinguish whether a repo is really "empty" or "broken"
 func (repo *Repository) MarkAsBrokenEmpty() {
 	repo.Status = RepositoryBroken
 	repo.IsEmpty = true