fix(dnd): mobile item reorder works via long-press instead of scrolling

PointerSensor also receives touch-derived pointer events and its 5px
distance constraint fired before the TouchSensor's hold delay - the
browser claimed the gesture for scrolling (pointercancel) and the drag
died. Replaced with MouseSensor (desktop unchanged), TouchSensor now
activates on a 300ms hold (tolerance 8px), and all drag handles carry
touch-action: none so the browser never starts a scroll from them.
Applies to DocumentItemsEditor (offers/issued orders) and the invoice
items list.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/admin/pages/InvoiceDetail.tsx

@@ -31,7 +31,7 @@ import {
   DndContext,
   closestCenter,
   KeyboardSensor,
-  PointerSensor,
+  MouseSensor,
   TouchSensor,
   useSensor,
   useSensors,
@@ -278,7 +278,11 @@ function SortableInvoiceRow({
             {...listeners}
             title="Přetáhnout"
             aria-label="Přetáhnout"
-            sx={{ cursor: "grab", color: "text.secondary" }}
+            sx={{
+              cursor: "grab",
+              color: "text.secondary",
+              touchAction: "none",
+            }}
           >
             {DragIcon}
           </IconButton>
@@ -388,7 +392,7 @@ function SortableInvoiceRow({
           {...listeners}
           title="Přetáhnout"
           aria-label="Přetáhnout"
-          sx={{ cursor: "grab", color: "text.secondary" }}
+          sx={{ cursor: "grab", color: "text.secondary", touchAction: "none" }}
         >
           {DragIcon}
         </IconButton>
@@ -511,10 +515,16 @@ export default function InvoiceDetail() {
     [],
   );
 
+  // MouseSensor (NOT PointerSensor): PointerSensor also receives touch-derived
+  // pointer events and its 5px distance constraint fires before the
+  // TouchSensor's long-press delay — the browser then claims the gesture for
+  // scrolling (pointercancel) and the drag dies. Mouse handles desktop,
+  // TouchSensor handles touch via long-press; the drag handles additionally
+  // carry touch-action: none so the browser never starts a scroll from them.
   const dndSensors = useSensors(
-    useSensor(PointerSensor, { activationConstraint: { distance: 5 } }),
+    useSensor(MouseSensor, { activationConstraint: { distance: 5 } }),
     useSensor(TouchSensor, {
-      activationConstraint: { delay: 200, tolerance: 5 },
+      activationConstraint: { delay: 300, tolerance: 8 },
     }),
     useSensor(KeyboardSensor),
   );