Global event listeners for drag-and-drop are added in onMount and removed in onDestroy. This is inefficient as they are active throughout the component's lifecycle, even when no drag is occurring. This can lead to performance degradation and potential conflicts with other parts of the application.

A more performant and robust approach is to attach these listeners to the window object only when a drag operation begins (i.e., in tabPointerDown) and remove them once it's complete (in a cleanup function called from draggingPointerUp and other abort scenarios).

To implement this, you can:

1. Remove the onMount and onDestroy lifecycle hooks for these listeners.
2. Add window.addEventListener(...) for pointermove, pointerup, mousedown, and keydown inside tabPointerDown.
3. Add window.removeEventListener(...) for the same events inside abortDrag.

P2: Accessing dragState.startIndex without a null check. dragState is typed DragState | undefined and the enclosing if condition doesn't narrow it. Add an explicit guard to avoid a potential runtime TypeError.

Check if this issue is valid — if so, understand the root cause and fix it. At frontend/src/components/window/Panel.svelte, line 142:

<comment>Accessing `dragState.startIndex` without a null check. `dragState` is typed `DragState | undefined` and the enclosing `if` condition doesn't narrow it. Add an explicit guard to avoid a potential runtime `TypeError`.</comment>

<file context>
@@ -58,19 +74,139 @@
+
+	function draggingPointerUp() {
+		if (dragInPanel && dragDropIndex !== undefined) {
+			reorderAction?.(dragState.startIndex, dragDropIndex);
+			justFinishedDrag = true;
+			// Clear after the current tick so a same-tick click is still suppressed, but the next intentional click is not swallowed
</file context>