Give each role's reboot handler its own name

pi_standard_setup, pi_hifiberry_amp and pi_disable_onboard_bluetooth each defined a
handler called "Reboot". Handler names are play-global, so a notify ran only the last
one defined - pi_disable_onboard_bluetooth's - and with that role's `when:`. On every
host where onboard Bluetooth stays on, the handler was skipped and nothing that asked
for a reboot ever got one: not a changed dtoverlay, not a hostname change, not the Pi 5
kernel. Seen on musicdolphin, where a new HiFiBerry overlay sat unapplied in
config.txt after a clean run.

Each role now notifies a handler only it defines.

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

roles/pi_standard_setup/tasks/main.yml

@@ -61,7 +61,7 @@
   when: pi_standard_setup_new_hostname | length > 0 and pi_standard_setup_pi_hostname.stdout != pi_standard_setup_new_hostname
   register: pi_standard_setup_set_hostname
   changed_when: true
-  notify: Reboot
+  notify: Reboot after standard setup
 - name: Get hostname
   ansible.builtin.command: "raspi-config nonint get_hostname"
   register: pi_standard_setup_pi_hostname
@@ -121,7 +121,7 @@
     cache_valid_time: 7200
     state: present
   when: pi_standard_setup_install_pi5_kernel
-  notify: Reboot
+  notify: Reboot after standard setup
 - name: Copy vim config
   ansible.builtin.copy:
     src: vimrc