fix(icom): send the leftover-waveform kill blind, at connect

The first attempt sent it only after CI-V answered — but the waveform flood
is what stops CI-V answering, so a rig wedged streaming never received its
cure. It now goes out at the end of Connect, before anything waits on a
reply: an unanswered set costs one frame, and the rig acts on what it decodes
whether or not we hear the acknowledgement.

internal/cat/icomserial.go

@@ -262,6 +262,17 @@ func (b *IcomSerial) Connect() error {
 	// non-default address still RENDERS; this flag only drives the SET/read commands
 	// (mode, span, edges), which need the 0x00 selector to be accepted on the 7300.
 	b.dualScope = idAddr == 0x98 || idAddr == 0xA2 || idAddr == 0x94
+	// Silence any LEFTOVER waveform stream, BLIND, before anything else. The
+	// 0x27 output flag lives in the RADIO and survives sessions; its flood is
+	// what makes the IC-7760 stop answering CI-V — so waiting for CI-V to
+	// answer before sending this (the first attempt did) was the egg asking
+	// the chicken to hatch it. Fire-and-forget: an unanswered set costs one
+	// frame, and the rig acts on what it decodes whether or not we hear the
+	// acknowledgement. The front-panel display is deliberately untouched.
+	// Synchronously: Connect already runs on the CAT goroutine, and a stray
+	// goroutine writing to the shared link would interleave with the command
+	// loop. One 350 ms wait at most, once per connect.
+	_ = b.execScope("waveform output off (leftover)", civ.SubScopeOn, 0)
 	// Defer the DSP snapshot until the rig actually answers CI-V. Over the network
 	// the rig may still be booting (or off) at Connect, so an immediate readDSP
 	// would time out and leave every control at 0 / off with no retry. ReadState
@@ -473,12 +484,6 @@ func (b *IcomSerial) ReadState() (RigState, error) {
 		if !b.dspLoaded {
 			b.readDSP()
 			b.dspLoaded = true
-			// Silence any LEFTOVER waveform stream. The 0x27 output flag lives
-			// in the RADIO and survives our sessions: a scope enabled by an older
-			// build (or another program) kept flooding every new session — and on
-			// the IC-7760 that flood is what kills the CI-V link. The display on
-			// the rig's front panel is deliberately untouched.
-			_ = b.execScope("waveform output off (leftover)", civ.SubScopeOn, 0)
 		} else {
 			b.refreshFrontPanel()
 		}