feat(tci): the transmit meters, and no temperature invented

TX_POWER and TX_SWR are read-only commands the radio answers when asked,
so they are asked for on each poll of a KEYED radio and not at all
otherwise: a receiving station pays nothing for meters nobody is watching.
Both appear next to the S-meter only while transmitting, because showing
them the rest of the time would show the last thing that happened as if it
were now.

An SWR of 0 draws as '—' rather than as 1.0. A perfect match on an antenna
nobody has measured is the one reading an operator should never be handed.

There is no temperature. The protocol's command list has TX_POWER and
TX_SWR and nothing thermal at all — so rather than leave the question
hanging, it is written down where the next person will look for it. A
temperature invented from something else, on a transmitter, is exactly the
kind of number somebody would trust.

internal/cat/yaesu_panel.go

@@ -51,13 +51,13 @@ type YaesuTXState struct {
 	// NarrowSupported says the rig answered NA at all. A button that reports a
 	// state the radio never gave, and does nothing when pressed, is worse than
 	// an absent one: it looks like a fault in the radio.
-	NarrowSupported bool `json:"narrow_supported"`
-	MicGain int    `json:"mic_gain"` // 0-100
-	AFGain  int    `json:"af_gain"`  // 0-100
-	RFGain  int    `json:"rf_gain"`  // 0-100
-	Squelch int    `json:"squelch"`  // 0-100
-	AGC     string `json:"agc,omitempty"`
-	Preamp  int    `json:"preamp"` // 0=IPO, 1=AMP1, 2=AMP2
+	NarrowSupported bool   `json:"narrow_supported"`
+	MicGain         int    `json:"mic_gain"` // 0-100
+	AFGain          int    `json:"af_gain"`  // 0-100
+	RFGain          int    `json:"rf_gain"`  // 0-100
+	Squelch         int    `json:"squelch"`  // 0-100
+	AGC             string `json:"agc,omitempty"`
+	Preamp          int    `json:"preamp"` // 0=IPO, 1=AMP1, 2=AMP2
 	// Antenna is the selected jack, 1-3, or 0 when the rig has no AN command —
 	// an FT-891 or FT-991A has a single socket and answers nothing. 0 is what
 	// tells the panel to draw no selector at all rather than a dead one.