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/PlexPlayerSettings.tsx

@@ -3,6 +3,7 @@ import { useTranslation } from "react-i18next";
 
 import { Slider, Toggle } from "./plexPlayerControls";
 import { clockParts, type PlexPlayerPrefs } from "../lib/plexPlayerPrefs";
+import { Pressable } from "./ui/Pressable";
 
 type SettingsTab = "sync" | "playback" | "subtitle" | "clock";
 
@@ -44,15 +45,17 @@ export function PlexPlayerSettings(props: {
     >
       <div className="mb-1.5 flex gap-1">
         {settingsTabs.map((tab) => (
-          <button
+          <Pressable
             key={tab.key}
+            align="center"
+            aria-pressed={activeTab === tab.key}
             onClick={() => setSettingsTab(tab.key)}
             className={`flex-1 whitespace-nowrap rounded px-2 py-1 text-2xs ${
               activeTab === tab.key ? "bg-white/15 text-accent" : "text-white/70 hover:bg-white/10"
             }`}
           >
             {tab.label}
-          </button>
+          </Pressable>
         ))}
       </div>
 
@@ -253,8 +256,10 @@ export function PlexPlayerSettings(props: {
           {prefs.clockDate && (
             <div className="flex gap-1 px-1 py-1">
               {(["hu", "en"] as const).map((st) => (
-                <button
+                <Pressable
                   key={st}
+                  align="center"
+                  aria-pressed={prefs.clockDateStyle === st}
                   onClick={() => patchPrefs({ clockDateStyle: st })}
                   className={`flex-1 rounded px-2 py-1 text-2xs ${
                     prefs.clockDateStyle === st
@@ -263,7 +268,7 @@ export function PlexPlayerSettings(props: {
                   }`}
                 >
                   {clockParts(now, { ...prefs, clockDate: true, clockDateStyle: st }).date}
-                </button>
+                </Pressable>
               ))}
             </div>
           )}