Rename every remaining voxip name to daynivo, with a one-time migration

Services (daynivo-kiosk-*, daynivo-network-guard, daynivo-boot-import),
programs in /usr/lib/daynivo-kiosk, folders /etc, /var/lib, /var/log and
/var/cache daynivo-kiosk*, the system user daynivo, DAYNIVO_* settings,
the plymouth theme, network profiles daynivo-eth0/wlan0, the image stage
and its first user daynivoadmin.

install.sh moves a kiosk installed up to 1.2.x over once: old services
stopped and removed, folders moved (configuration, password, browser
profile, logs) with symlinks under the old names, the voxip user renamed
with the same uid, network profiles renamed unless a change awaits
confirmation, and old leftovers removed. Tested by upgrading a configured
1.2.0 installation in a container, and running the install a second time.

Old names keep working where people type or place them: voxip-config.json,
voxip-authorized_keys, voxip-network-reset, voxip-kiosk-ctl, and
VOXIP_DEFAULT_URL / VOXIP_DEVICE_NAME for image builds.

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

config/sudoers

@@ -1,4 +1,4 @@
-# Daynivo Kiosk OS: the web interface (user voxip) may run exactly one program
+# Daynivo Kiosk OS: the web interface (user daynivo) may run exactly one program
 # as root: the restricted helper, which validates all of its input itself.
-Defaults:voxip !requiretty
-voxip ALL=(root) NOPASSWD: /usr/lib/voxip-kiosk/voxip-kiosk-helper
+Defaults:daynivo !requiretty
+daynivo ALL=(root) NOPASSWD: /usr/lib/daynivo-kiosk/daynivo-kiosk-helper