diag: log SteppIR status frames so a stuck "moving" (TX interlock) is visible

The SteppIR client logged commands it sent but never the status frames it read
back, so a misread motor-status byte — which drives the app's "block TX while
the antenna is moving" interlock on a FlexRadio — was invisible. Log the raw
11-byte frame plus the decoded freq/dir/moving and the motor (buf[6]) and
direction (buf[7]) bytes, but only when the frame changes, to keep the 2 s poll
from flooding the log. Purely diagnostic; no behaviour change.

internal/steppir/steppir.go

@@ -23,6 +23,7 @@
 package steppir
 
 import (
+	"bytes"
 	"encoding/binary"
 	"fmt"
 	"io"
@@ -84,6 +85,12 @@ type Client struct {
 	lastStatus *Status
 	lastSetKHz int
 
+	// lastRaw holds the previous raw status frame so we only log a status line
+	// when the controller's reply actually changes — enough to diagnose a stuck
+	// "motors moving" read (which drives the app's TX-inhibit interlock) without
+	// spamming the log every 2 s poll.
+	lastRaw []byte
+
 	// A just-commanded direction is held until the controller's poll reports it —
 	// the motors take a second or two, and a stale poll would otherwise snap the
 	// UI back. Same trick as the Ultrabeam client.
@@ -242,7 +249,17 @@ func (c *Client) queryStatus() (*Status, error) {
 	if _, err := io.ReadFull(conn, buf); err != nil {
 		return nil, fmt.Errorf("read status: %w", err)
 	}
-	return parseStatus(buf)
+	st, err := parseStatus(buf)
+	// Log the raw frame + decode whenever it changes. The motor byte (buf[6]) is
+	// what decides st.MotorsMoving, and that in turn drives the app's "block TX
+	// while moving" interlock — so if a controller (e.g. with its INHIBIT engaged)
+	// reports a byte we misread as perpetual motion, this line makes it visible.
+	if err == nil && !bytes.Equal(buf, c.lastRaw) {
+		c.lastRaw = append(c.lastRaw[:0], buf...)
+		log.Printf("steppir: status ← % X  (freq=%d kHz dir=%d moving=%d motorByte=0x%02X dirByte=0x%02X)",
+			buf, st.Frequency, st.Direction, st.MotorsMoving, buf[6], buf[7])
+	}
+	return st, err
 }
 
 // parseStatus decodes an 11-byte status frame.