Stop the kiosk coming up blank after every reboot

A reboot kills Chromium rather than closing it, so it writes "exit_type":"Crashed" into
its profile. On the next boot it came up with a restore prompt and a tab stuck for ever
on a blank "Loading..." page - navigation never committed, navigator.serviceWorker was
still undefined, nothing on screen. On a device with a monitor and no keyboard that is
permanent, and the backend was healthy throughout: / answered in 5 ms and /api/library
returned 812 kB the whole time.

--disable-session-crashed-bubble hides the prompt but not the state behind it, and here
the prompt showed anyway. .xinitrc now rewrites exit_type and exited_cleanly before
launching, which is the usual remedy for a kiosk that gets powered off rather than shut
down, and adds --hide-crash-restore-bubble (the current name for the flag).

Verified by rebooting and leaving it alone: the page comes up on its own with its title
and its content.

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

roles/pi_musicmouse/handlers/main.yml

@@ -26,6 +26,15 @@
     src: "{{ pi_musicmouse_build_cache }}/{{ musicmouse_version | regex_replace('/', '_') }}/web/dist/"
     dest: /opt/musicmouse/web/dist/
     delete: true
+  notify: Record which commit the frontend was built from
+
+- name: Record which commit the frontend was built from
+  # After the sync, and outside dist/, which the sync empties of anything it did not
+  # build. This is what lets the next run tell a current dist from a stale one.
+  ansible.builtin.copy:
+    content: "{{ pi_musicmouse_web_checkout.after }}\n"
+    dest: /opt/musicmouse/web/.built-commit
+    mode: "0644"
   notify: Restart musicmouse
 
 - name: Restart musicmouse