fix: prevent stacked reorder mode from multiple 'Neu anordnen' clicks

Added _reorderCtx.active flag — plReorderEnter bails early if already
active, preventing duplicate handles and event listeners from stacking.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/views.js

@@ -587,7 +587,8 @@ function _setupReorderMode(container, songs, pl) {
 }
 
 export function plReorderEnter() {
-  if (!_reorderCtx) return;
+  if (!_reorderCtx || _reorderCtx.active) return;
+  _reorderCtx.active = true;
   const { container, songs } = _reorderCtx;
   container.classList.add('pl-draggable');
   // Block context-menu (long-press) on all items while reordering.
@@ -684,6 +685,7 @@ export function plReorderCancel() { _exitReorderMode(false); }
 function _exitReorderMode(save) {
   if (!_reorderCtx) return;
   const { container, songs, pl } = _reorderCtx;
+  _reorderCtx.active = false;
   container.classList.remove('pl-draggable');
   container.removeEventListener('contextmenu', _blockCtxMenu, true);
   container.querySelectorAll('.pl-drag-handle').forEach(h => h.remove());