ap: parallel 2.4GHz AP (hostapd-2g) on the Linksys WUSB6300v2 dongle

Second radio (wlxd8ec5e2faa8c, RTL8822BU/rtw88), same VanLink SSID+PSK,
ch6 HT20, bridged into br0 next to the 5GHz AP. Runs as its own hostapd
instance + own watchdog so a USB wedge on one radio never darkens the
other; van-ap-watchdog now takes conf path + unit name as args (defaults
unchanged). rtw88.conf disables deep power-save (rtw89 gotcha analog)
and the driver's USB2->3 self-upgrade (USB3 noise in the 2.4GHz band —
note: dongle currently sits in a USB3 port, so it still enumerates
SuperSpeed; move to a USB2 port if 2.4GHz range disappoints).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ap/hostapd-2g.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=VanLink 2.4GHz AP (hostapd on wlxd8ec5e2faa8c, RTL8822BU)
+# Same USB re-enumeration hazards as the 5GHz AP (see hostapd-restart.conf for the
+# full story): never stop retrying, and back off a few seconds so the USB device can
+# re-enumerate before the next attempt.
+StartLimitIntervalSec=0
+After=network.target
+
+[Service]
+ExecStart=/usr/sbin/hostapd /etc/hostapd/hostapd-2g.conf
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=multi-user.target