fix(kiosk): overlay scrollbars — no more fat X11 scrollbar on scrollable views

--enable-features=OverlayScrollbar gives the thin auto-hiding scrollbars a
remote browser shows (Peers view had a permanent classic scrollbar on the
TV). Rides the existing kiosk self-heal + ISO splice.

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

image-recipe/configs/archipelago-kiosk-launcher.sh

@@ -174,6 +174,9 @@ while true; do
     # backend can't find PipeWire-Pulse's socket at /run/user/<uid>/pulse/native,
     # falls back to raw ALSA "default", fails to connect, and produces no audio
     # at all with no visible error (--noerrdialogs suppresses it).
+    # OverlayScrollbar: thin auto-hiding scrollbars (the Chrome-on-a-remote-
+    # device look) instead of classic X11 scrollbar chrome — a kiosk TV showed
+    # a permanent fat scrollbar on scrollable views (Peers).
     # Force a DARK color-scheme preference. The main UI hardcodes its dark
     # theme, but the bundled AIUI app themes via `@media (prefers-color-scheme)`
     # and defaults to its LIGHT variant (white panels) when the browser reports
@@ -191,6 +194,7 @@ while true; do
       --no-first-run \
       --check-for-update-interval=31536000 \
       --disable-features=TranslateUI,MetricsReporting,AutofillServerCommunication,PasswordManagerEnabled,GpuRasterization \
+      --enable-features=OverlayScrollbar \
       --disable-session-crashed-bubble \
       --disable-save-password-bubble \
       --disable-suggestions-service \