debug(rigctld): always trace a client's first six commands

A connect that lasts 50 ms leaves nothing to say which answer the client
disliked — WSJT-X refusing to attach to the shared CAT was undiagnosable
without the full wire trace. The handshake is now always logged; steady-state
polling stays behind the trace switch.

internal/rigctld/rigctld.go

@@ -246,6 +246,11 @@ func (s *Server) serve(c net.Conn) {
 		s.releasePTT(fmt.Sprintf("client %s left", c.RemoteAddr()))
 	}()
 	s.log("rigctld: client connected from %s", c.RemoteAddr())
+	// The HANDSHAKE is always traced — the first few commands are where a
+	// client decides to stay or hang up, and a connect that lasted 50 ms left
+	// nothing in the log to say which answer it disliked. Steady-state polling
+	// stays behind the CAT trace switch.
+	traced := 0
 	r := bufio.NewReader(c)
 	w := bufio.NewWriter(c)
 	for {
@@ -265,7 +270,8 @@ func (s *Server) serve(c net.Conn) {
 		// that preceded it — the one thing needed to tell whether OpsLog answered
 		// something the client could not accept. Behind the same switch as the CAT
 		// wire trace: this is one line per poll and would drown an ordinary log.
-		if req != "" && cat.CIVTraceEnabled() {
+		if req != "" && (traced < 6 || cat.CIVTraceEnabled()) {
+			traced++
 			s.log("rigctld: %s → %q ⇒ %q", c.RemoteAddr(), req, strings.TrimRight(resp, "\r\n"))
 		}
 		if resp != "" {