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/ErrorBoundary.tsx

@@ -3,6 +3,7 @@ import i18n from "../i18n";
 import { notify } from "../lib/notifications";
 import { errorAttrs, log } from "../lib/log";
 import { reloadingForNewBuild } from "../lib/staleBuild";
+import { Button } from "./ui/Button";
 
 interface Props {
   children: ReactNode;
@@ -46,12 +47,9 @@ export default class ErrorBoundary extends Component<Props, State> {
               {i18n.t("errors.boundary.title")}
             </div>
             <div className="text-sm mb-3">{i18n.t("errors.boundary.subtitle")}</div>
-            <button
-              onClick={() => location.reload()}
-              className="text-accent hover:underline text-sm font-semibold"
-            >
+            <Button variant="link" onClick={() => location.reload()} className="text-sm">
               {i18n.t("errors.boundary.reload")}
-            </button>
+            </Button>
           </div>
         </div>
       );