Get sound, the screen and emoji working on musicdolphin's Pi 5

- HiFiBerry: the plain hifiberry-dacplus overlay makes the Pi the I2S clock consumer,
  which the Pi 5's controller refuses (snd_soc_dai_set_fmt -22). The card never probed,
  so every softvol_* device was dead: squeezelite crash-looped and the backend and
  shairport played into nothing. hifiberry-dacplus-std has the Pi drive the clocks.
  pi_hifiberry_amp now matches any dtoverlay=hifiberry-* line, so changing the overlay
  replaces the old one instead of adding a second.
- X: with two DRM devices (v3d, vc4) Xorg gave up with "Cannot run in framebuffer
  mode", and the kiosk looped on a blank screen. 99-vc4.conf points it at vc4, the
  display controller; rendering still goes to V3D (glxinfo: V3D 7.1, accelerated).
- The front-end's icons are emoji in the markup. The Lite image has no emoji font, so
  they rendered as empty boxes: install fonts-noto-color-emoji.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

host_vars/musicdolphin.yml

@@ -4,7 +4,10 @@ pi_shairport_name: _Oben_Wohnzimmer
 alsa_card_name: sndrpihifiberry
 sensor_room_name_ascii: wohnzimmeroben
 sensor_room_name: WohnzimmerOben
-hifiberry_overlay: hifiberry-dacplus
+# -std: the Pi drives the I2S clocks. The plain dacplus overlay makes the Pi the clock
+# consumer, which the Pi 5's I2S controller rejects (snd_soc_dai_set_fmt -22), so the
+# card never probes and every softvol_* device is dead.
+hifiberry_overlay: hifiberry-dacplus-std
 main_user: root
 
 mediapi_has_hifiberry_amp: true