fix(playlists): what the first review of bulk actions found

An Esc during a pointer drag is spent on the drag and leaves the selection.
A wheel over the rail re-reads the target each frame, so a drop lands on the
row under the pointer. After a bulk removal the focus goes to the next row
left, and to the list's menu when the list is emptied.

remove-bulk names the videos that went, and its Undo brings back only those.
An Undo of a move keeps each row (and when it was saved), leaves out a video
that moved on from the target, closes up its place, and says how many came
back. Delete with every tick hidden removes nothing and says why. A list gone
before the lock answers 404, and a body without its videos 422.

One removal path now: the single row goes through the bulk one, the same
toast and undo, which also retires the add-at-position route. railDrop reuses
the store and scrollParent, the drag image the overlay and the z-index token,
and the sensors keep their number. The count is read out from a region that
outlives the band. Tests fill the gaps the review named, each seen failing.

frontend/src/modules/playlists/SelectionBand.tsx

@@ -1,4 +1,4 @@
-import type { ReactNode, Ref } from "react";
+import type { MouseEventHandler, ReactNode, Ref } from "react";
 import { useTranslation } from "react-i18next";
 import { ChevronDown, FolderInput, History, ListRestart, Square, X } from "lucide-react";
 import { Button } from "../../components/ui/Button";
@@ -8,7 +8,8 @@ import { Button } from "../../components/ui/Button";
  *  it leaves alone. With only hidden ones the actions stay in place, off, and the way out stays on.
  *  Below `xl` the buttons are glyphs named in their tooltips: in words the row wraps there, and the
  *  first tick would push the list from under the second tap. On a phone the count is its number and
- *  the undo pair stays out, for the same one row. */
+ *  the undo pair stays out, for the same one row. The page says the count out loud: this band goes
+ *  when the selection does, and a live region that leaves with its news announces nothing. */
 export function SelectionBand({
   ref,
   count,
@@ -33,14 +34,14 @@ export function SelectionBand({
   onRemove: () => void;
   onClear: () => void;
   /** The view's reset, which the row this one replaces offers. */
-  onClearView?: () => void;
+  onClearView?: MouseEventHandler<HTMLButtonElement>;
   trailing: ReactNode;
 }) {
   const { t } = useTranslation();
   const none = count === 0;
   return (
     <div ref={ref} className="flex items-center gap-1 mt-1 flex-wrap xl:gap-2">
-      <span role="status" className="text-xs whitespace-nowrap">
+      <span className="text-xs whitespace-nowrap">
         <span className="sr-only font-medium sm:not-sr-only">
           {t("playlists.selectedCount", { count })}
         </span>