feat: Yaesu control panel (meters, bands, DSP, TX), and drop a stale Flex hint

A console pane for the native Yaesu backend, in the same shape as the Icom and
Flex ones: S/PO/SWR meters, band and mode rows, AF/RF/squelch, AGC, the IPO/AMP1/
AMP2 front-end selector, ATT, NB, DNR + level, narrow filter, power in watts, mic
gain, VOX, split and ATU tune.

Three decisions worth keeping:

Panel reads are STAGGERED and live in their own file, away from ReadState. Meters
poll every cycle; settings only change when someone turns a knob, so they refresh
every 8th cycle and right after any set. Polling all of it every cycle would put
twenty queries a second on the serial link the frequency display shares.

Band buttons use the rig's own band memory (BS) rather than a frequency we pick,
so 20 m lands where the operator last was on 20 m — what the radio's own band
keys do.

A set is followed by a read-back, so the panel shows what the RIG ended up with,
not what we asked for; the two differ whenever a value is out of range or the
mode forbids the control. And a control the model lacks keeps its previous value
instead of dropping to zero, which reads as a setting that reset itself.

The S9 point of the S-meter scale is a hypothesis (the manual does not state it)
and is commented as such — one number to correct if reports come out an S unit
off, rather than a fudge spread through the RST helper.

Also removes the FlexRadio settings blurb, which explained the backend to
someone who had already chosen it.

frontend/wailsjs/go/main/App.js

@@ -946,6 +946,10 @@ export function GetWinkeyerStatus() {
   return window['go']['main']['App']['GetWinkeyerStatus']();
 }
 
+export function GetYaesuState() {
+  return window['go']['main']['App']['GetYaesuState']();
+}
+
 export function HasBuiltinReferences(arg1) {
   return window['go']['main']['App']['HasBuiltinReferences'](arg1);
 }
@@ -1458,6 +1462,10 @@ export function RefreshSolar() {
   return window['go']['main']['App']['RefreshSolar']();
 }
 
+export function RefreshYaesuPanel() {
+  return window['go']['main']['App']['RefreshYaesuPanel']();
+}
+
 export function ReloadUDPIntegrations() {
   return window['go']['main']['App']['ReloadUDPIntegrations']();
 }
@@ -1770,6 +1778,66 @@ export function SetWinkeyerTrace(arg1) {
   return window['go']['main']['App']['SetWinkeyerTrace'](arg1);
 }
 
+export function SetYaesuAFGain(arg1) {
+  return window['go']['main']['App']['SetYaesuAFGain'](arg1);
+}
+
+export function SetYaesuAGC(arg1) {
+  return window['go']['main']['App']['SetYaesuAGC'](arg1);
+}
+
+export function SetYaesuAtt(arg1) {
+  return window['go']['main']['App']['SetYaesuAtt'](arg1);
+}
+
+export function SetYaesuBand(arg1) {
+  return window['go']['main']['App']['SetYaesuBand'](arg1);
+}
+
+export function SetYaesuMicGain(arg1) {
+  return window['go']['main']['App']['SetYaesuMicGain'](arg1);
+}
+
+export function SetYaesuNB(arg1) {
+  return window['go']['main']['App']['SetYaesuNB'](arg1);
+}
+
+export function SetYaesuNR(arg1) {
+  return window['go']['main']['App']['SetYaesuNR'](arg1);
+}
+
+export function SetYaesuNRLevel(arg1) {
+  return window['go']['main']['App']['SetYaesuNRLevel'](arg1);
+}
+
+export function SetYaesuNarrow(arg1) {
+  return window['go']['main']['App']['SetYaesuNarrow'](arg1);
+}
+
+export function SetYaesuPower(arg1) {
+  return window['go']['main']['App']['SetYaesuPower'](arg1);
+}
+
+export function SetYaesuPreamp(arg1) {
+  return window['go']['main']['App']['SetYaesuPreamp'](arg1);
+}
+
+export function SetYaesuRFGain(arg1) {
+  return window['go']['main']['App']['SetYaesuRFGain'](arg1);
+}
+
+export function SetYaesuSplit(arg1) {
+  return window['go']['main']['App']['SetYaesuSplit'](arg1);
+}
+
+export function SetYaesuSquelch(arg1) {
+  return window['go']['main']['App']['SetYaesuSquelch'](arg1);
+}
+
+export function SetYaesuVOX(arg1) {
+  return window['go']['main']['App']['SetYaesuVOX'](arg1);
+}
+
 export function StartCWDecoder() {
   return window['go']['main']['App']['StartCWDecoder']();
 }
@@ -1842,6 +1910,10 @@ export function TestUltrabeam(arg1) {
   return window['go']['main']['App']['TestUltrabeam'](arg1);
 }
 
+export function TuneYaesuATU() {
+  return window['go']['main']['App']['TuneYaesuATU']();
+}
+
 export function TunerGeniusActivate(arg1) {
   return window['go']['main']['App']['TunerGeniusActivate'](arg1);
 }