refactor(winkeyer): learn the slow boot instead of naming the keyer

The K3NG entry added an hour ago is gone. It named one clone among many —
WKmini, home-built Arduinos, unbranded boxes — for hardware that speaks
exactly the same protocol, and it was the only line in the engine list that
picked a boot delay rather than a protocol. An operator with an unlabelled
clone would have had to guess.

The delay is now learnt per port. The first connect finds out by failing the
quick attempt and succeeding on the slow one; that fact is written to a
global setting keyed by the port, and every connect afterwards goes straight
to the slow attempt. Global rather than per profile on purpose: which keyer
is plugged into COM3 belongs to the computer, and switching profiles for a
different rig does not change the keyer on the desk.

Two tests hold the contract from both sides — a slow keyer must be reported
as slow, and a keyer that answers at once must not be, or every K1EL connect
would inherit seconds it never needed.

frontend/src/components/SettingsModal.tsx

@@ -3884,7 +3884,6 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
                 <SelectTrigger className="h-8"><SelectValue /></SelectTrigger>
                 <SelectContent>
                   <SelectItem value="winkeyer">{t('wk.engWinkeyer')}</SelectItem>
-                  <SelectItem value="k3ng">{t('wk.engK3ng')}</SelectItem>
                   <SelectItem value="serial">{t('wk.engSerial')}</SelectItem>
                   <SelectItem value="icom">{t('wk.engIcom')}</SelectItem>
                   <SelectItem value="yaesu">{t('wk.engYaesu')}</SelectItem>