fix(oxibadge): accept hostnames and FQDNs for the time clock address

The "Edit address" field in Settings only accepted an IPv4 address
(IPV4.test), rejecting a bare hostname (e.g. "timbratore") or FQDN
(e.g. "timbratore.lan") even though the underlying connection (Rust's
ToSocketAddrs) already resolves those fine. Onboarding had no such
restriction. Replaced the IPv4-only check with isValidHost (IPv4 OR a
standard DNS hostname), dropped the numeric-only keyboard hint on that
field, and reworded the labels/placeholder error to not imply IP-only.

Also makes "Edit address" test the connection before accepting it,
instead of saving unconditionally: ActionButton gained a `disabled`
prop so the confirm/cancel buttons can be locked (with a spinner on
confirm) while the test is in flight, and the edit form now only
closes on a successful test, staying open with the raw error shown
otherwise.

Assisted-by: Claude Sonnet 5 <noreply@anthropic.com>

oxibadge/src/lib/locales/it.json

@@ -2,8 +2,8 @@
   "loading": "Caricamento...",
   "onboarding": {
     "title": "Benvenuto!",
-    "subtitle": "Collega Oxibadge al tuo timbratore inserendo il suo indirizzo IP e la porta.",
-    "host_label": "Indirizzo IP",
+    "subtitle": "Collega Oxibadge al tuo timbratore inserendo il suo indirizzo e la porta.",
+    "host_label": "Indirizzo",
     "port_label": "Porta",
     "hint": "Trovi l'indirizzo nelle impostazioni di rete del timbratore.",
     "button": {
@@ -136,9 +136,9 @@
     "status_idle": "Non verificato",
     "edit_address": "Modifica indirizzo",
     "test_connection": "Testa connessione",
-    "ip_label": "Indirizzo IP",
+    "ip_label": "Indirizzo",
     "port_label": "Porta",
-    "ip_invalid": "Formato non valido, es. 192.168.1.100",
+    "ip_invalid": "Formato non valido, es. 192.168.1.100 o timbratore.lan",
     "cancel": "Annulla",
     "confirm": "Conferma",
     "shifts_title": "Turni previsti",