Desktop: drop the VAULT columns that had nothing in them, and the snippet buttons with nothing to act on

src/DodoSSH.Client.Shell/ViewModels/VaultViewModel.cs

@@ -2404,6 +2404,14 @@ internal sealed partial class VaultViewModel(
 
     internal bool HasVaultItems => VaultItems.Count > 0;
 
+    /// <summary>Whether any row in the keychain table names a vault, which is whether its VAULT column has a heading.</summary>
+    /// <remarks>
+    /// Read off the rows rather than off how many vaults there are, because a row's badge is what the column
+    /// holds: the two agree today — see <see cref="VaultItemRowViewModel.VaultBadge"/> — and if they ever stop
+    /// agreeing, a heading over nothing is the thing this exists to avoid.
+    /// </remarks>
+    internal bool ShowsVaultColumn => VaultItems.Any(row => row.HasVaultBadge);
+
     internal bool HasSelectedVaultItem => SelectedVaultItem is not null;
 
     /// <summary>
@@ -13457,6 +13465,16 @@ internal sealed partial class VaultViewModel(
         };
     }
 
+    /// <summary>Re-reads what the keychain table says about its rows as a whole.</summary>
+    private void RaiseVaultItemFacts()
+    {
+        OnPropertyChanged(nameof(SectionSummary));
+        OnPropertyChanged(nameof(HasVaultItems));
+        OnPropertyChanged(nameof(ShowsVaultColumn));
+        OnPropertyChanged(nameof(TotalItemCount));
+        OnPropertyChanged(nameof(EmptySectionMessage));
+    }
+
     /// <summary>── v5b ── Narrows <see cref="VaultItems"/> to rows <see cref="ItemFilter"/> matches.</summary>
     /// <remarks>
     /// Its own method for the reason <see cref="AddTagRows"/> is out of <see cref="RebuildVaultItems"/> —
@@ -13552,10 +13570,7 @@ internal sealed partial class VaultViewModel(
         // sync every minute would otherwise move the detail pane out from under whoever was reading it.
         SelectedVaultItem = VaultItems.FirstOrDefault(row => row.EntityId == selectedId);
 
-        OnPropertyChanged(nameof(SectionSummary));
-        OnPropertyChanged(nameof(HasVaultItems));
-        OnPropertyChanged(nameof(TotalItemCount));
-        OnPropertyChanged(nameof(EmptySectionMessage));
+        RaiseVaultItemFacts();
 
         // A reload replaces every row object, and the selection is restored by id — so the setter above may
         // not have fired even though the row this answers about is a different instance. Asked again here,