feat(qt): move a playlist to a folder from its editor, delete one from any context menu

The editor gains a Folder row — the same folders the sidebar and the
manager file playlists into, "No folder" for the root — seeded from the
playlist's current folder and applied on Save through the manager's own
move verb, so an existing playlist no longer needs the sidebar's row menu
to be filed (#785). "Delete playlist" joins the sidebar row menu (own and
local playlists; sidebar entries now carry isOwner) and the playlist card
menu (own playlists), behind a shell-level "Delete playlist?" confirmation
that runs the same delete the editor's button runs and leaves the detail
page only when it was the deleted one (#776). Eight catalogs updated.

cc

crates/qbz-qt/qml/shell/AppShell.qml

@@ -950,6 +950,13 @@ Rectangle {
     PlaylistEditModal {
         anchors.fill: parent
     }
+    // PlaylistDeleteConfirm — the "Delete playlist?" confirmation the sidebar
+    // row menu and the playlist cards summon (QbzPlaylistEdit.askDelete).
+    // Self-gates on QbzPlaylistEdit.deleteJson; invisible and inert while
+    // closed. Out here for the same reason as FolderModals above.
+    PlaylistDeleteConfirm {
+        anchors.fill: parent
+    }
     // PlaylistCreateModal — "New playlist" (name · description · folder ·
     // public · offline-only), raised by the sidebar's "+" and, like its
     // neighbour, self-gating on its own document (QbzPlaylistEdit.createJson).

crates/qbz-qt/qml/shell/SidebarRowMenu.qml

@@ -89,6 +89,10 @@ QbzContextMenu {
 
     readonly property bool isFolder: root.entry !== null && root.entry.kind === "folder"
     readonly property bool isLocal: root.entry !== null && root.entry.isLocal === true
+    /// The signed-in user owns the Qobuz playlist (sidebar_qt stamps it);
+    /// a local playlist is always the user's own.
+    readonly property bool isOwner: root.entry !== null
+        && (root.entry.isLocal === true || root.entry.isOwner === true)
     readonly property string entryId: root.entry !== null ? String(root.entry.id) : ""
     readonly property string entryFolderId:
         (root.entry !== null && root.entry.folderId) ? String(root.entry.folderId) : ""
@@ -261,6 +265,19 @@ QbzContextMenu {
         }
     }
     // Divider before the move-to-folder section — Qobuz only.
+    // Delete (2026-09-13): the fast path the editor's danger button already
+    // offers, one click from the row, behind the shell-level confirmation
+    // (PlaylistDeleteConfirm.qml). Owned Qobuz playlists and local ones only;
+    // a followed playlist keeps its Unfollow elsewhere.
+    MenuRow {
+        visible: !root.isFolder && root.isOwner
+        icon: "trash-2"
+        label: QbzSession.tr("Delete playlist", QbzSession.trRev)
+        onActivated: {
+            root.close()
+            QbzPlaylistEdit.askDelete(root.entryId, String(root.entry.name))
+        }
+    }
     Item {
         visible: !root.isFolder && !root.isLocal
         width: parent ? parent.width : 0