Daynivo names for the files on the SD card and the command line tool

- daynivo-config.json, daynivo-authorized_keys and daynivo-network-reset
  on the boot partition; errors go to daynivo-config.error.txt.
- daynivo-kiosk-ctl, with voxip-kiosk-ctl as a symlink to it.
- The voxip-* names keep working, so existing SD cards and instructions
  stay valid; when both config files are present the Daynivo one is
  applied last.
- Internal names (services, /etc/voxip-kiosk, user voxip) are unchanged.

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

image/daynivo-config.example.json

@@ -0,0 +1,10 @@
+{
+  "device_name": "Hal begane grond",
+  "url": "https://schermen-ijsselflat.voxip.nl",
+  "hostname": "hal-bg",
+  "wifi_country": "NL",
+  "refresh_interval": 0,
+  "rotation": 0,
+  "resolution": "auto",
+  "screen_always_on": true
+}