Switch musicdolphin from a Pi 4 to a Pi 5

The SD card moves over as is, so:
- pi_standard_setup can install the Pi 5 kernel (linux-image-rpi-2712, an arm64
  package on the armhf userland), which a Pi 4 image lacks. Opt-in via
  pi_standard_setup_install_pi5_kernel.
- The Pi is powered through the HiFiBerry board's GPIO header, so it cannot negotiate
  a 5A supply and would cap USB at 600mA. pi_hifiberry_amp sets
  usb_max_current_enable=1 when hifiberry_powers_pi is true (default false).
- The DHT22 poller is off: Adafruit_DHT bit-bangs BCM283x registers, which the Pi 5
  no longer has (GPIO sits behind the RP1 chip).

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

roles/pi_standard_setup/tasks/main.yml

@@ -115,6 +115,13 @@
       - telnet
     cache_valid_time: 7200
     state: present
+- name: Install the Pi 5 kernel
+  ansible.builtin.apt:
+    name: "linux-image-rpi-2712:arm64"
+    cache_valid_time: 7200
+    state: present
+  when: pi_standard_setup_install_pi5_kernel
+  notify: Reboot
 - name: Copy vim config
   ansible.builtin.copy:
     src: vimrc