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/ui/ActionMenu.tsx

@@ -2,6 +2,8 @@ import { Fragment, useState, type ReactNode } from "react";
 import { ChevronRight, MoreHorizontal } from "lucide-react";
 import { PopoverItem, PopoverSurface } from "./AnchoredPopover";
 import { closeThenAct, useAnchoredPopover } from "./anchoredPopoverHooks";
+import { IconButton } from "./IconButton";
+import { Pressable } from "./Pressable";
 
 // A reusable "⋯ more actions" overflow menu: a compact trigger that opens a list of one-shot actions.
 // Built on the R8 AnchoredPopover platform (arrows/typeahead/Escape/anchor-flip), same as ViewSwitcher
@@ -209,19 +211,28 @@ export default function ActionMenu({
   const pop = useAnchoredPopover({ open, onOpenChange: setOpen, placement: "bottom-end" });
   return (
     <>
-      <button
-        type="button"
-        ref={pop.refs.setReference}
-        {...pop.getReferenceProps()}
-        aria-label={ariaLabel}
-        title={ariaLabel}
-        className={
-          className ??
-          "glass-card glass-hover flex items-center justify-center rounded-xl p-2 text-sm transition"
-        }
-      >
-        {trigger ?? <MoreHorizontal className="h-5 w-5" aria-hidden="true" />}
-      </button>
+      {/* A caller-shaped trigger (a labelled pill) is a surface; the default "…" is a glyph. */}
+      {className ? (
+        <Pressable
+          ref={pop.refs.setReference}
+          {...pop.getReferenceProps()}
+          aria-label={ariaLabel}
+          title={ariaLabel}
+          className={className}
+        >
+          {trigger ?? <MoreHorizontal className="h-5 w-5" aria-hidden="true" />}
+        </Pressable>
+      ) : (
+        <IconButton
+          variant="glass"
+          size="md"
+          ref={pop.refs.setReference}
+          {...pop.getReferenceProps()}
+          label={ariaLabel}
+        >
+          {trigger ?? <MoreHorizontal aria-hidden="true" />}
+        </IconButton>
+      )}
       <PopoverSurface popover={pop} ariaLabel={ariaLabel} className={MENU_SURFACE}>
         <MenuItemList items={items} onClose={() => setOpen(false)} />
       </PopoverSurface>