feat(design): every button on its family, the chip primitive, the lint rule (E28 S3b2)

The second half of the button sweep: the remaining hand-rolled buttons in
feature components, the design lab and the components/ui composites now
stand on Button, IconButton, Pressable, Chip or DragHandle.

- Chip + DismissibleChip (filter / token / tag / suggest / ghost, 24px
  floor, 44 on touch) replace five chip geometries; FilterChipGroup
  renders Chips; overflow lanes measure a mirror painted by chipClass.
- The Plex control row is IconButton's player rung (36, 20px glyph,
  round, overlay; 44 on touch); the YT modal bar is on the sm rung with
  pressed cycle toggles and names that survive a folded label.
- New variants: IconButton ghost-accent, danger-soft; Button warn on a
  new state-warn utility. The .btn-{tone} recipes and btnCls are gone.
- Fixed on the way: membership rows (collection editor, Plex playlist
  add) announce checked/mixed; a one-letter tag chip was 21px wide;
  descriptionLinks moved out of lib/ (it renders components).
- local/button-primitive: a raw <button>/<FocusSafeButton> outside the
  control-primitive files is a lint error (contract-tested, seen red).

frontend/src/i18n/locales/en/playlists.json

@@ -98,7 +98,6 @@
   "removeItem": "Remove",
   "removeItemOf": "Remove “{{title}}” from the playlist",
   "confirmRemove": "Remove “{{title}}” from this playlist?",
-  "dragHandle": "Drag to reorder",
   "dragHandleOf": "Reorder “{{title}}”",
   "dragBlockedSort": "Reordering by hand is off while a column sort or grouping is applied.",
   "dragBlockedFilter": "Reordering by hand is off while a filter is applied.",

frontend/src/i18n/locales/hu/playlists.json

@@ -98,7 +98,6 @@
   "removeItem": "Eltávolítás",
   "removeItemOf": "„{{title}}” eltávolítása a listáról",
   "confirmRemove": "Eltávolítod a(z) „{{title}}” videót erről a listáról?",
-  "dragHandle": "Húzd az átrendezéshez",
   "dragHandleOf": "„{{title}}” átrendezése",
   "dragBlockedSort": "A kézi átrendezés ki van kapcsolva, amíg oszloprendezés vagy csoportosítás van érvényben.",
   "dragBlockedFilter": "A kézi átrendezés ki van kapcsolva, amíg szűrő van érvényben.",