Drop Wi-Fi power save toggling in favor of keeping it off

The on-battery toggle bought a fraction of a watt while the radio
idled -- twenty-some minutes across a full discharge in the best case
-- and paid for it with 20-300ms latency spikes on idle links and
outright link drops on Intel BE200/BE211 firmware. NetworkManager can
keep power save off natively with one conf.d line, which replaces the
udev rule, the setter script, and any per-card deny-listing.

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

migrations/1784914435.sh

@@ -0,0 +1,19 @@
+echo "Keep Wi-Fi power save off for lower latency"
+
+as_root() {
+  if (( EUID == 0 )); then
+    "$@"
+  else
+    sudo "$@"
+  fi
+}
+
+as_root nmcli general reload conf >/dev/null 2>&1 || true
+
+# NetworkManager only applies wifi.powersave when a connection activates, so
+# also switch it off directly for the running session.
+shopt -s nullglob
+for wireless in /sys/class/net/*/wireless; do
+  iface=$(basename "$(dirname "$wireless")")
+  as_root iw dev "$iface" set power_save off 2>/dev/null || true
+done