fix(qt): Shift and Ctrl work on every select-mode click target, not only the row body

Excel-style selection (750c59034) read the modifiers only where a row BODY
took the click. Every other target a select-mode surface draws dropped them,
so a Shift-click there was a plain toggle:

  - the track row's checkbox disc passed Qt.NoModifier;
  - QbzCheckbox and SelectCheck emitted toggled() with no argument, so the
    Library album rows, the local album rows and the folder rows, which
    already expected `function (mods)`, received undefined;
  - AlbumCard emitted selectToggled() with no argument, and the paged local
    albums grid (299dcde5b) spelled the drop out as Qt.NoModifier.

Some targets were never selection targets at all: in select mode the artist
and album names on a track row, the artist and label on a Library album row
and the artist line of an album card still navigated, leaving the page and
the selection mid-gesture. The row links stand down in select mode so the
click reaches the row body with its modifiers, and the card's artist line
toggles like its artwork and title. A hover-only tooltip on the pulled but
cached glyph no longer eats the row's click.

Reproduced on the release binary in a nested KWin with injected input: in
Local Library Tracks, the checkbox discs of rows 1, Shift 4 and Ctrl 6
selected 3 rows; the same clicks on the row bodies selected 5. No list
view, Flickable or wheel code changes; tst_wheel passes unchanged.

tst_multi_select clicks each of these targets through the real TrackRow,
AlbumListRow, AlbumCard, QbzCheckbox and SelectCheck.

cc

crates/qbz-qt/qml/views/local/LocalAlbumCollection.qml

@@ -593,11 +593,14 @@ Item {
                                 selected: root.nativeActive
                                     ? cardCell.slot.selected === true
                                     : root.selected[cardCell.slot.id] === true
-                                onSelectToggled: {
+                                // The card's modifiers, straight through: the
+                                // paged grid (299dcde5b) passed NoModifier here,
+                                // so a Shift-click on a card was a toggle.
+                                onSelectToggled: function (mods) {
                                     if (root.nativeActive)
-                                        root.nativeToggleSelect(cardCell.slot.nativeIndex, Qt.NoModifier)
+                                        root.nativeToggleSelect(cardCell.slot.nativeIndex, mods)
                                     else
-                                        root.toggleSelect(cardCell.slot.id, Qt.NoModifier)
+                                        root.toggleSelect(cardCell.slot.id, mods)
                                 }
                                 // Non-select mode only — the card routes a
                                 // select-mode click to `selectToggled` and never

crates/qbz-qt/qml/views/local/SelectCheck.qml

@@ -5,6 +5,10 @@
 // Slint declares this inline inside TreeRow; the Qt port also needs it on
 // the album cards and the track rows in multi-select, so it is its own file
 // (three call sites, one shape).
+//
+// `toggled` carries the click's modifiers: this disc IS a select-mode click
+// target, and one that dropped them turned every Shift-click on it into a
+// plain toggle (controls/SelectionModel.qml).
 
 import QtQuick
 import com.blitzfc.qbz
@@ -16,7 +20,7 @@ Rectangle {
     property bool on: false
     property bool partial: false
     property int diameter: 13
-    signal toggled()
+    signal toggled(int modifiers)
 
     QbzTheme { id: theme }
 
@@ -52,6 +56,6 @@ Rectangle {
         anchors.fill: parent
         hoverEnabled: true
         cursorShape: Qt.PointingHandCursor
-        onClicked: root.toggled()
+        onClicked: function (mouse) { root.toggled(mouse.modifiers) }
     }
 }