Each printer now has one MQTT connection that stays open, merging the
partial reports printers send while printing. Cards poll every 3 seconds
(paused while the tab is hidden) and show state, file, progress with time
left and finish time, layer, nozzle/bed/chamber temperatures, speed
setting, and print error and HMS codes. A spool change syncs the Filament
page and the card's drawing within seconds; a full report is requested
every 10 minutes as a backstop, replacing the 10-minute probe loop.
"Test & sync" uses the open connection rather than making a second one
(?debug=1 still makes a short separate one). Connections are reconciled
when printers are added, edited or removed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
