feat(sat): Doppler tracking on the radio

The hard part of satellite tuning is not the arithmetic, it is deciding
who owns the dial. A tracker that forces both frequencies fights the
operator every time they turn the knob to follow a station across a
linear transponder; one that never touches the receiver leaves them
chasing a signal that slides nine kilohertz across a 70 cm pass.

So the operator owns the receiver and the tracker follows them. Every
second it asks the radio where the receiver actually is. Where it put it,
nothing has changed. Further than a dial-turn's tolerance, and the
operator has chosen a station: what they landed on is converted back into
a nominal frequency, and the transmitter is derived from that. Which is
the division of labour on a linear bird — the operator listens, the radio
does the sums.

Three ways to reach the radio, because a satellite pair is a shape of
operating rather than a manufacturer's feature. An IC-9700 or IC-9100 is
asked for its OWN satellite mode: it pairs main and sub, gives full
duplex, and keeps the dials linked the way its designers meant, which is
always better than an imitation built out of split. A Flex gets two
slices, A the downlink and B the uplink, created when missing, because
"slice B does not exist" is not something to make an operator fix at the
start of a ten-minute pass. Everything else gets the downlink, and is
told so — half the job announced beats half the job hidden.

What goes in the log is the NOMINAL pair. Two stations working each other
through a transponder read different numbers off their dials at the same
instant; the only figure they can both agree on is the transponder's own.
FREQ is the uplink and FREQ_RX the downlink — the one place a satellite
QSO differs from every other kind, and the reason FREQ alone cannot
describe one.

internal/cat/icomserial.go

@@ -94,6 +94,13 @@ type IcomSerial struct {
 	// reassembled sweep; scopeMu guards it (written by the scope goroutine, read
 	// via ScopeData from the binding goroutine).
 	dualScope bool
+	// satNative marks the two-band satellite rigs — the IC-9700 and the IC-9100 —
+	// which have a real satellite mode of their own. Everything else gets the
+	// downlink and, where the uplink is reachable, split.
+	satNative bool
+	// satOn tracks what we last told the rig, so TuneSatellite can arm the mode
+	// once rather than on every Doppler step.
+	satOn bool
 	// Set when the rig rejects the waveform-output command in both shapes: it has
 	// no stream to give, and asking again on every enable is noise.
 	scopeUnsupported bool
@@ -284,6 +291,10 @@ func (b *IcomSerial) Connect() error {
 	// non-default address still RENDERS; this flag only drives the SET/read commands
 	// (mode, span, edges), which need the 0x00 selector to be accepted on the 7300.
 	b.dualScope = idAddr == 0x98 || idAddr == 0xA2 || idAddr == 0x94
+	// The satellite rigs: IC-9700 and IC-9100. Both carry two receivers on two
+	// bands and a satellite mode that pairs them; no other Icom in this table
+	// does, and asking one that does not is a rejected frame per Doppler step.
+	b.satNative = idAddr == 0xA2 || idAddr == 0x7C
 	// Silence any LEFTOVER waveform stream, BLIND, before anything else. The
 	// 0x27 output flag lives in the RADIO and survives sessions; its flood is
 	// what makes the IC-7760 stop answering CI-V — so waiting for CI-V to