feat(elecraft): a K3/K4 console — power, volume, S-meter, SWR, MOX, tune

The Elecraft backend already existed; what was missing was somewhere to
operate the radio from. This adds the panel, on the Kenwood-dialect
client the K3 already speaks, in a tab of its own beside the Yaesu and
Icom consoles.

Scope is the six controls asked for and nothing else. Every extra command
added without a radio to test it against is a control that may or may not
do what its label says, and a K3 exposes dozens.

No K3 was available while writing this, so the two halves are treated
differently. The setters are the commands the reference documents
unambiguously and whose effect is visible and reversible (PC, AG,
TX/RX). The meters are the opposite: their scaling differs by model and
firmware, so the raw answers are logged next to the power setting, the
panel says the scaling is provisional, and an unmeasured SWR shows as
'—' rather than as a perfect 1.0 — a good match on an antenna nobody
measured is the reading that costs a radio.

ATU tune sends SWT20 (the K3 front-panel tap) and logs exactly what it
sent, so a wrong mapping names itself instead of leaving an operator
guessing which button OpsLog pressed.

frontend/wailsjs/go/main/App.js

@@ -914,6 +914,10 @@ export function GetIcomState() {
   return window['go']['main']['App']['GetIcomState']();
 }
 
+export function GetKenwoodState() {
+  return window['go']['main']['App']['GetKenwoodState']();
+}
+
 export function GetLinkedAmps() {
   return window['go']['main']['App']['GetLinkedAmps']();
 }
@@ -1738,6 +1742,10 @@ export function RefreshCtyDat() {
   return window['go']['main']['App']['RefreshCtyDat']();
 }
 
+export function RefreshKenwood() {
+  return window['go']['main']['App']['RefreshKenwood']();
+}
+
 export function RefreshSolar() {
   return window['go']['main']['App']['RefreshSolar']();
 }
@@ -2138,10 +2146,22 @@ export function SetFlexRSTChaseEnabled(arg1) {
   return window['go']['main']['App']['SetFlexRSTChaseEnabled'](arg1);
 }
 
+export function SetKenwoodAFGain(arg1) {
+  return window['go']['main']['App']['SetKenwoodAFGain'](arg1);
+}
+
 export function SetKenwoodKeySpeed(arg1) {
   return window['go']['main']['App']['SetKenwoodKeySpeed'](arg1);
 }
 
+export function SetKenwoodPower(arg1) {
+  return window['go']['main']['App']['SetKenwoodPower'](arg1);
+}
+
+export function SetKenwoodTX(arg1) {
+  return window['go']['main']['App']['SetKenwoodTX'](arg1);
+}
+
 export function SetLinkedAmps(arg1) {
   return window['go']['main']['App']['SetLinkedAmps'](arg1);
 }
@@ -2354,6 +2374,10 @@ export function TestWebPublishFTP(arg1) {
   return window['go']['main']['App']['TestWebPublishFTP'](arg1);
 }
 
+export function TuneKenwoodATU() {
+  return window['go']['main']['App']['TuneKenwoodATU']();
+}
+
 export function TuneYaesuATU() {
   return window['go']['main']['App']['TuneYaesuATU']();
 }