Three bugs: (1) home_flag bit 18 is set on all printers regardless
of connection type, so every ethernet-capable model showed the badge
even on WiFi. Replaced with wifi_signal heuristic — ethernet printers
with WiFi disabled report a hardcoded -90 dBm sentinel. (2) The lazy
import used `from app.utils.printer_models` which crashes with
ModuleNotFoundError in paho-mqtt's background thread (correct path:
backend.app.utils.printer_models). This killed the thread, causing
all printers to go stale after 60s and disconnect/reconnect in a
loop. (3) WiFi-only models excluded via model-based gating.
maziggy
2e7529a540