Bulk-select a channel's videos into a playlist; last card no longer hidden under the bottom bars

- Channel pages join the select-mode views: tap Select in the filter row, pick
  videos (or Select all — respects the filter), then + Queue / + Playlist.
  Delete is hidden there (nothing to delete on a channel).
- --bottom-chrome (the fixed bottom nav + mini player height) is now measured
  whenever the mini player shows/hides and on resize/rotation, not only while
  the section rail scrolls, and the list pane pads its end by it, so the last
  card scrolls fully clear with or without the mini player.

frontend/styles.css

@@ -4306,3 +4306,7 @@ body.landscape-fs .player-stage { touch-action: none; } /* fullscreen (real or t
 
 /* iPhone/iPad: no double-tap page zoom (scrolling unaffected) */
 html.ios-nozoom, html.ios-nozoom body { touch-action: manipulation; }
+
+/* The last card of a list scrolls clear of the bottom nav + mini player
+   (--bottom-chrome is measured in app.js updateBottomChrome). */
+#listPane { padding-bottom: calc(var(--bottom-chrome, 0px) + 32px) !important; }