fix(yaesu): mic gain scale, 200 W models, and a NAR button that did nothing

Reported from a real FTDX101, and each one is a different kind of wrong.

MIC GAIN was read and written through the 0-255 scale the audio gains
use, but the CAT reference gives MG000-100. A rig set to 80 therefore
showed 38, and moving the slider sent 204 — outside the range the radio
accepts, so it refused the command and the slider sprang back. That
snap-back was the symptom; the scale was the cause.

POWER was capped at 100 W by the slider, not by the radio. There is no
CAT command for 'how much power can you make', so the ceiling comes from
the model name, with the rig believed if it ever reports more than the
table expects — it has just proved what it can do.

NAR is the narrow IF filter, and on a rig that does not implement NA the
button showed a state the radio never gave and did nothing when pressed,
which reads as a fault in the radio. Now shown only when the rig answers,
with a tooltip saying what it is.

Also: the frequency readout steps the Hz digits under the wheel, not just
the kHz ones. Zero-beating a CW signal is a few tens of Hz and it was the
one move the display would not make. And the split chaser is CW-only —
its marker comes from a CW skimmer.

frontend/src/components/FlexPanel.tsx

@@ -677,6 +677,10 @@ export function FlexPanel({ onCWSpeed, onReportRST }: { onCWSpeed?: (wpm: number
                   in the log, which is done mid-QSO with one hand. The offset
                   sits beside it because it is the one number retuned while
                   chasing — everything else about the feature is configured once. */}
+              {/* CW ONLY. The marker comes from a skimmer decoding a CW report,
+                  so on SSB or FT8 there is nothing to chase — and a switch that
+                  cannot fire is an invitation to wonder why it does nothing. */}
+              {isCW && (<>
               <button type="button" disabled={off}
                 title={t('flxp.rstChaseHint', { m: rstChase.markers })}
                 onContextMenu={(e) => { e.preventDefault(); setRstChaseEditing(true); }}
@@ -725,6 +729,7 @@ export function FlexPanel({ onCWSpeed, onReportRST }: { onCWSpeed?: (wpm: number
                   Hz
                 </label>
               )}
+              </>)}
               {st.split && !!st.tx_freq_hz && (
                 <span className="text-[11px] font-mono text-muted-foreground whitespace-nowrap">
                   TX {(st.tx_freq_hz / 1e6).toFixed(3)}