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/vite.config.ts

@@ -60,8 +60,9 @@ export default defineConfig({
     port: 5173,
     proxy,
     // What an e2e run writes is no source. On Windows a file it is rewriting answers the watcher with
-    // EBUSY, which takes the whole dev server down; each run also reloaded every open page.
-    watch: { ignored: ["**/playwright-report/**", "**/test-results/**"] },
+    // EBUSY, which takes the whole dev server down; each run also reloaded every open page. (Its
+    // `test-results` is a default of vite's, and `ignored` adds to the defaults.)
+    watch: { ignored: ["**/playwright-report/**", "**/e2e/.auth/**"] },
   },
   build: { outDir: "dist", rollupOptions: { input: ["index.html", "watch.html"] } },
 });