fix(ultrabeam): accept an 11-byte status frame from older controllers

An older controller behind an RS232-to-Ethernet bridge returns the status frame
without its trailing FreqMax byte (11 bytes, not 12). The packet checksum is
still valid, so it's a real short frame, not a fragment. queryStatus now accepts
>= 10 bytes and defaults the missing FreqMin/FreqMax rather than rejecting it as
"too short", which reconnect-looped the link. Whether the byte LAYOUT is
otherwise identical across controller versions still needs confirming from the
protocol reference.

internal/ultrabeam/ultrabeam.go

@@ -509,7 +509,13 @@ func (c *Client) queryStatus() (*Status, error) {
 		return nil, err
 	}
 
-	if len(reply) < 12 {
+	// An older controller — seen behind an RS232-to-Ethernet bridge — answers with
+	// an 11-byte status frame: the standard one WITHOUT the trailing FreqMax byte.
+	// The packet checksum was already verified, so a short-but-valid frame is real,
+	// not a fragment. Accept it and default the missing tail fields instead of
+	// reconnect-looping on "reply too short". reply[9]/[10] (MotorsMoving, FreqMin)
+	// are the last we truly need, so 10 bytes is the floor.
+	if len(reply) < 10 {
 		return nil, fmt.Errorf("status reply too short: %d bytes", len(reply))
 	}
 
@@ -522,8 +528,12 @@ func (c *Client) queryStatus() (*Status, error) {
 		Direction:        int(reply[6] & 0x0F),
 		OffState:         (reply[7] & 0x02) != 0,
 		MotorsMoving:     int(reply[9]),
-		FreqMin:          int(reply[10]),
-		FreqMax:          int(reply[11]),
+	}
+	if len(reply) > 10 {
+		status.FreqMin = int(reply[10])
+	}
+	if len(reply) > 11 {
+		status.FreqMax = int(reply[11])
 	}
 
 	return status, nil