feat(k3): a mode row on the Elecraft console — CW/USB/LSB/DATA/DATA-RTTY

The report: switching the K3 to a data mode 'does not work for FT8 — the K3
does not go into DATA'. The mode digit is only half the answer on that radio:
MD6 keeps whatever DT submode the previous session left, and with FSK D still
armed the rig keys FT8 with no rear-audio modulation.

The panel buttons say the whole thing: DATA is MD6+DT0 (DATA A, the soundcard
path), DATA RTTY is MD6+DT2 (FSK D). The DT submode is also read on the
settings beat — Elecraft only, a plain Kenwood would '?;' it — so the active
DATA button follows what the rig is actually in, front-panel changes included.
A dedicated SetKenwoodPanelMode rather than the logger's SetMode: a panel
button is the operator saying exactly what the rig should do, not an ADIF mode
to be mapped through preferences.

frontend/src/components/ElecraftPanel.tsx

@@ -4,7 +4,7 @@ import {
   GetKenwoodState, RefreshKenwood, SetKenwoodPower, SetKenwoodAFGain, SetKenwoodTX, TuneKenwoodATU,
   SetKenwoodRFGain, SetKenwoodMicGain, SetKenwoodSquelch, SetKenwoodPreamp, SetKenwoodAtt,
   SetKenwoodNB, SetKenwoodNR, SetKenwoodAGC, SetKenwoodFilter, SetKenwoodAntenna,
-  SetKenwoodRIT, SetKenwoodXIT, ClearKenwoodRIT, SetKenwoodKeySpeed, ToggleKenwoodATU, NudgeKenwoodRIT,
+  SetKenwoodRIT, SetKenwoodXIT, ClearKenwoodRIT, SetKenwoodKeySpeed, ToggleKenwoodATU, NudgeKenwoodRIT, SetKenwoodPanelMode,
   GetCATState,
 } from '../../wailsjs/go/main/App';
 import { cn } from '@/lib/utils';
@@ -14,7 +14,7 @@ import { MeterBar } from '@/components/MeterBar';
 import { WheelRange } from '@/components/WheelRange';
 
 type KenwoodState = {
-  available: boolean; model?: string; elecraft: boolean; mode?: string;
+  available: boolean; model?: string; elecraft: boolean; mode?: string; data_sub?: string;
   transmitting: boolean; split: boolean; split_tx_hz?: number;
   s_meter: number; s_meter_raw: number;
   power_meter: number; swr: number; swr_raw: number;
@@ -89,6 +89,16 @@ function Toggle({ label, on, off, onClick }: { label: string; on: boolean; off:
   );
 }
 
+// isDataMode: what the rig reports for MD6 varies — "DATA", or the configured
+// digital default (FT8…) — so the DATA family is "not one of the native modes".
+function isDataMode(m?: string): boolean {
+  switch ((m ?? '').toUpperCase()) {
+    case '': case 'CW': case 'USB': case 'LSB': case 'SSB': case 'FM': case 'AM': case 'RTTY':
+      return false;
+  }
+  return true;
+}
+
 export function ElecraftPanel({ onReportRST }: { onReportRST?: (rst: string) => void }) {
   const { t } = useI18n();
   const [st, setSt] = useState<KenwoodState>(ZERO);
@@ -149,6 +159,28 @@ export function ElecraftPanel({ onReportRST }: { onReportRST?: (rst: string) =>
             {freqHz > 0 ? (freqHz / 1e6).toFixed(6) : '—'}
           </div>
         </div>
+        {/* Mode row. The two DATA buttons are why it exists: MD6 alone keeps
+            whatever submode the last session left, and a K3 "in DATA" with FSK D
+            still armed keys FT8 with no audio. DATA sends MD6+DT0 (DATA A, the
+            soundcard path), RTTY sends MD6+DT2 (FSK D). The active DATA button
+            follows the rig's own DT answer. */}
+        <div className="inline-flex rounded-md border border-border overflow-hidden">
+          {([
+            ['CW', 'CW', view.mode === 'CW'],
+            ['USB', 'USB', view.mode === 'USB'],
+            ['LSB', 'LSB', view.mode === 'LSB'],
+            ['DATA', t('k3.modeData'), isDataMode(view.mode) && view.data_sub !== 'FSK D' && view.data_sub !== 'PSK D'],
+            ['RTTY', t('k3.modeRtty'), (isDataMode(view.mode) && (view.data_sub === 'FSK D' || view.data_sub === 'PSK D')) || view.mode === 'RTTY'],
+          ] as [string, string, boolean][]).map(([cmd, label, on]) => (
+            <button key={cmd} type="button" disabled={off}
+              title={cmd === 'DATA' ? t('k3.modeDataHint') : cmd === 'RTTY' ? t('k3.modeRttyHint') : label}
+              onClick={() => SetKenwoodPanelMode(cmd).catch((e: any) => setErr(String(e?.message ?? e)))}
+              className={cn('px-2.5 py-1.5 text-xs font-bold border-l border-border first:border-l-0',
+                on ? 'bg-primary text-primary-foreground' : 'bg-card text-muted-foreground hover:bg-muted')}>
+              {label}
+            </button>
+          ))}
+        </div>
         <button type="button" className="text-[11px] text-muted-foreground hover:text-foreground flex items-center gap-1"
           onClick={() => RefreshKenwood().catch(() => {})} title={t('k3.refreshHint')}>
           <SlidersHorizontal className="size-3.5" />