Give previously-bare panels a keyed background so the existing dark-UI walk
can theme them. Runtime-created widgets (HMS items, device firmware/nozzle
panels) route their whole subtree through one UpdateDarkUIWin(this) call
instead of per-widget darkModeColorFor, which also themes their child text
and follows live light/dark switches. Extruder-card chips re-apply their
colours from Sidebar::sys_color_changed so a live switch updates them too.
Multi-nozzle sync widget, AMS rack-nozzle mapping popup, calibration rework, send-dialog nozzle mapping and extruder-count UI. Includes the fix to persist the AMS sync badge on filament cards (H2C/A2L and direct-sync printers).