Skip all personal devices from ARP seed, not just labeled ones

Operator needs ARRIVED for any phone or wearable on site, including
unknown devices. Silent seeding only applies to infrastructure and
non-personal devices.

net_alerter/net_alerter.py

@@ -827,12 +827,10 @@ def seed_from_arp_cache():
             if mac == "00:00:00:00:00:00" or flags == "0x0":
                 continue
 
-            # Labeled personal devices must NOT be silently seeded — they need
-            # a real on_arrival call so ARRIVED fires when they rejoin.
-            # Just update last_seen as a baseline so the watchdog has a reference.
-            with personal_lock:
-                is_personal = mac in device_labels or mac in personal_devices
-            if is_personal:
+            # Personal devices (phones, wearables — any LAA MAC, known mobile OUI,
+            # or explicitly labeled MAC) must NOT be silently seeded. The operator
+            # needs ARRIVED for every device they don't already know about.
+            if is_personal_device(mac):
                 with last_seen_lock:
                     if mac not in last_seen:
                         last_seen[mac] = time.time()