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/components/PlexCollectionEditor.tsx

@@ -9,7 +9,7 @@ import { useScrollFade } from "../lib/useScrollFade";
 import { Button } from "./ui/Button";
 import Modal from "./ui/Modal";
 import { useConfirm } from "./confirmContext";
-import { FocusSafeButton } from "./ui/FocusSafeButton";
+import { Pressable } from "./ui/Pressable";
 
 // Admin-only "manage this movie's collections" dialog (Collections P2). Lists the library's EDITABLE
 // collections with an in/out toggle (add/remove the movie, written back to Plex), plus a field to
@@ -191,10 +191,12 @@ export default function PlexCollectionEditor({
                 key={c.id}
                 className="glass-card flex items-center gap-2 rounded-lg px-2 py-1.5 text-sm"
               >
-                <FocusSafeButton
+                <Pressable
+                  role="checkbox"
+                  aria-checked={inIt}
                   onClick={() => toggle(c.id)}
                   disabled={!!busy}
-                  className={`inline-flex min-w-0 flex-1 items-center gap-2 text-left disabled:opacity-50 ${
+                  className={`inline-flex min-w-0 flex-1 items-center gap-2 disabled:opacity-50 ${
                     inIt ? "text-accent" : ""
                   }`}
                 >
@@ -209,14 +211,15 @@ export default function PlexCollectionEditor({
                   <span className="shrink-0 text-xs text-muted">
                     {t("plex.collEditor.count", { count: c.child_count ?? 0 })}
                   </span>
-                </FocusSafeButton>
-                <FocusSafeButton
+                </Pressable>
+                <Button
+                  variant="outline-danger"
+                  size="xs"
                   onClick={() => removeCollection(c.id, c.title)}
                   disabled={!!busy}
-                  className="shrink-0 rounded-sm px-1.5 py-0.5 text-xs text-muted hover:text-danger disabled:opacity-50"
                 >
                   {t("plex.collEditor.delete")}
-                </FocusSafeButton>
+                </Button>
               </div>
             );
           })
@@ -243,13 +246,14 @@ export default function PlexCollectionEditor({
                 <span className="shrink-0 text-xs text-muted">
                   {t("plex.collEditor.count", { count: c.child_count ?? 0 })}
                 </span>
-                <FocusSafeButton
+                <Button
+                  variant="glass"
+                  size="xs"
                   onClick={() => markEditable(c.id)}
                   disabled={!!busy}
-                  className="glass-card glass-hover shrink-0 rounded-sm px-2 py-0.5 text-xs disabled:opacity-50"
                 >
                   {t("plex.collEditor.makeEditable")}
-                </FocusSafeButton>
+                </Button>
               </div>
             ))}
           </div>