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>

image/boot-README.txt

@@ -8,7 +8,7 @@ een fout; de reden staat dan in daynivo-config.error.txt).
 
 daynivo-config.json
     Instellingen voor deze kiosk. Zie daynivo-config.example.json. Toegestaan:
-    alle sleutels uit /etc/voxip-kiosk/config.json plus "hostname" en
+    alle sleutels uit /etc/daynivo-kiosk/config.json plus "hostname" en
     "wifi_country". Voorbeeld:
 
       {
@@ -20,7 +20,7 @@ daynivo-config.json
 
 daynivo-authorized_keys
     Openbare SSH-sleutels (één per regel). SSH wordt dan ingeschakeld, alleen
-    met sleutel-login, voor de beheerder (voxipadmin of de gebruiker die je
+    met sleutel-login, voor de beheerder (daynivoadmin of de gebruiker die je
     in Raspberry Pi Imager hebt aangemaakt).
 
 daynivo-network-reset