feat(audit): Batch 20 — Windows/main-process (UI23, W12, W15, L131)

UI23: cookie sign-in + PO-token windows open with the app's resolved
theme background (passed from the IPC layer), no more white flash.
W12: multi-resolution fallback tray icon (16/24/32/48 via
addRepresentation dataURL, embedded in trayFallbackIcons.ts); decode +
scale factors verified in an Electron probe.
W15: hardwareAcceleration setting (default false = software rendering);
index.ts gates disableHardwareAcceleration on it after the portable
redirect; Appearance card switch with restart note; boot path verified.
L131: resolved by-design — clearing the queue acknowledges failures;
flashFrame (W10) covers attention, Diagnostics persists the record.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/renderer/src/components/SettingsView.tsx

@@ -62,7 +62,11 @@ type CardComponent = () => React.JSX.Element
  * state instead of mutating the card's own DOM `style` (M14).
  */
 const SECTIONS: { id: string; title: string; cards: CardComponent[] }[] = [
-  { id: 'downloads', title: 'Downloads', cards: [DownloadsCard, PostProcessingCard, FilenamesCard] },
+  {
+    id: 'downloads',
+    title: 'Downloads',
+    cards: [DownloadsCard, PostProcessingCard, FilenamesCard]
+  },
   { id: 'appearance', title: 'Appearance', cards: [AppearanceCard] },
   { id: 'network', title: 'Network & accounts', cards: [NetworkCard, CookiesCard] },
   { id: 'advanced', title: 'Advanced', cards: [CustomCommandsCard] },

src/renderer/src/components/settings/AppearanceCard.tsx

@@ -1,5 +1,13 @@
 import { useRef } from 'react'
-import { Field, Button, Card, Subtitle2, Caption1, mergeClasses } from '@fluentui/react-components'
+import {
+  Field,
+  Button,
+  Card,
+  Subtitle2,
+  Caption1,
+  Switch,
+  mergeClasses
+} from '@fluentui/react-components'
 import { PaintBucketRegular, AccessibilityRegular } from '@fluentui/react-icons'
 import { type ThemeMode, type AccentColor } from '@shared/ipc'
 import { useSettings } from '../../store/settings'
@@ -20,6 +28,7 @@ export function AppearanceCard(): React.JSX.Element {
   const focus = useFocusStyles()
   const theme = useSettings((s) => s.theme)
   const accentColor = useSettings((s) => s.accentColor)
+  const hardwareAcceleration = useSettings((s) => s.hardwareAcceleration)
   const highContrast = useSystemTheme((s) => s.shouldUseHighContrastColors)
   const update = useSettings((s) => s.update)
   // Store action wraps the IPC call (L93/CC13: no window.api in components).
@@ -91,6 +100,16 @@ export function AppearanceCard(): React.JSX.Element {
         </div>
       </Field>
 
+      <Field
+        label="Hardware acceleration"
+        hint="Uses the GPU to draw the window (takes effect after you restart AeroFetch). Off by default: some older GPUs render the window blank with this on — turn it back off if that happens."
+      >
+        <Switch
+          checked={hardwareAcceleration}
+          onChange={(_, d) => update({ hardwareAcceleration: d.checked })}
+        />
+      </Field>
+
       <Caption1 className={styles.hint}>
         {highContrast
           ? 'A Windows high-contrast theme is active -- AeroFetch follows your system colors.'