fix(kpa): its own card, and no band-follow it does not need

Two things the wiring got wrong, both visible on screen.

A KPA fell through to the PowerGenius branch of the amplifier card and was
drawn as one — titled 'POWERGENIUSXL · ELECRAFT KPA1500', with a
PowerGenius's meters and none of its own. It has a card now: OPERATE, ON
and OFF, band, power, SWR, temperature, supply, and the fault across the
end. The OPERATE button carries a tooltip saying it also clears the fault,
because that is the button an operator already has under the cursor when
they need it.

And the band-follow option was offered on it. That option exists because
an Acom POLLS a transceiver and has no command to be given a band, so
following it needs a second serial port and a rig emulator answering those
polls. The KPA has ^BN — OpsLog simply tells it, on the link it is already
using, and only when the band CHANGES. The option is gone from the KPA and
the telling is automatic.

Also: Acom rather than ACOM everywhere it is read, which is how the
company writes it. Identifiers, package names and log lines are left
alone — renaming those is churn with no reader.

internal/kpa/kpa.go

@@ -372,3 +372,41 @@ func (c *Client) pollOnce(n uint64) {
 		}
 	}
 }
+
+// SetBand puts the amplifier on a band by its ADIF name.
+//
+// The KPA takes its band from the transceiver on its own XCVR connector, but it
+// also accepts ^BN — so OpsLog can simply say it on the link it is already
+// using. That is worth knowing: an Acom has no such command, which is why
+// following it needs a second serial port and a transceiver emulator answering
+// its polls (internal/catemu). None of that applies here.
+//
+// Sent only when it CHANGES. Repeating the current band four times a second
+// would be traffic on a link with no flow control, in exchange for nothing.
+func (c *Client) SetBand(adifBand string) error {
+	n, ok := bandNumber(adifBand)
+	if !ok {
+		// Not an error the operator should see: the KPA covers 160-6 m, and
+		// tuning to 23 cm is not a fault, it is simply not this amplifier's
+		// business.
+		return nil
+	}
+	c.statusMu.Lock()
+	same := c.status.Band == adifBand
+	c.statusMu.Unlock()
+	if same {
+		return nil
+	}
+	return c.send(fmt.Sprintf("^BN%02d;", n))
+}
+
+// bandNumber is BandName backwards.
+func bandNumber(adifBand string) (int, bool) {
+	b := strings.ToLower(strings.TrimSpace(adifBand))
+	for n, name := range bandNames {
+		if name == b {
+			return n, true
+		}
+	}
+	return 0, false
+}