feat(cat): MY_RIG follows the radio that is connected

With one rig, MY_RIG belonged in Operating conditions and nowhere else.
With several, that becomes the wrong place: operating conditions describe
a PLAN — 'on 20 m I use the beam and the 7300' — while the question a
logged QSO asks is which radio was keying.

So each saved radio carries its own MY_RIG, consulted BEFORE the per-band
station. When the two disagree — a second rig borrowed for one evening on
20 m — the one that is transmitting is the true answer.

Left empty it changes nothing at all: the old chain (band default, then
the profile's rig) answers exactly as it did, which is what every
single-radio station will keep doing without touching a setting.

frontend/src/components/SettingsModal.tsx

@@ -3266,7 +3266,19 @@ function SettingsModalImpl({ onClose, onSaved, initialSection, onMainPaneChanged
                 <Trash2 className="size-3.5" />
               </Button>
             </div>
+            {/* MY_RIG follows the radio, not the profile.
+                Operating conditions describe a PLAN — "on 20 m I use the beam
+                and the 7300" — while this is the fact of which rig is keying.
+                Empty leaves the old chain alone. */}
+            <div className="flex items-center gap-2">
+              <Label className="shrink-0 w-24">{t('cat.radioMyRig')}</Label>
+              <Input className="h-9 flex-1" placeholder={t('cat.radioMyRigPh')}
+                value={(radios.find((r: any) => r.id === activeRadio)?.my_rig) ?? ''}
+                onChange={(e) => setRadios((l) => l.map((r: any) => r.id === activeRadio ? { ...r, my_rig: e.target.value } : r))}
+                onBlur={() => { SaveRadios(radios as any).catch(() => {}); }} />
+            </div>
             <p className="text-[11px] text-muted-foreground">{t('cat.radioHint')}</p>
+            <p className="text-[11px] text-muted-foreground">{t('cat.radioMyRigHint')}</p>
           </div>
 
           <label className="flex items-center gap-2 text-sm cursor-pointer">