Rename the visible VoxIP texts to Daynivo

Product name (Daynivo Kiosk OS), default device name, kiosk screens,
service descriptions, installer output and docs. Internal names
(voxip-kiosk-*, /etc/voxip-kiosk, user voxip, VOXIP_* variables) stay.
An update renames a device still called "VoxIP Kiosk" to the new default.

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

src/voxip_kiosk/web/templates/system.html

@@ -65,7 +65,7 @@
 <section class="card">
   <h2>Systeeminformatie</h2>
   <dl class="kv">
-    <dt>Versie</dt><dd>VoxIP Kiosk OS {{ s.version }}</dd>
+    <dt>Versie</dt><dd>Daynivo Kiosk OS {{ s.version }}</dd>
     <dt>Besturingssysteem</dt><dd>{{ s.os }}</dd>
     <dt>Hardware</dt><dd>{{ s.model }}</dd>
     <dt>Uptime</dt><dd>{{ s.uptime }}</dd>