feat(tci): key CW through the radio's own macro keyer

The sixth CW engine, and the one the TCI backend was left without. A SunSDR
keys from the WebSocket that already carries the CAT: no WinKeyer, no second
serial port, nothing to wire.

    CW_MACROS:0,<text>;     send
    CW_MACROS_SPEED:<wpm>;  speed
    CW_MACROS_STOP;         abort

Confirmed against the TCI command table in ars-ka0s/eesdr-tci — the source that
settled SPOT. CW_MACROS rather than TCI 2.0's CW_MSG: it exists from 1.6, and
OpsLog resolves its own variables, so the before/after callsign fields have
nothing to carry.

Commas and semicolons are stripped before sending. They are the protocol's own
separators: a comma would become another argument, a semicolon would end the
command with the message half keyed and the rest parsed as a command.

Only the MACRO speed is set, not the paddle keyer's — an operator who set their
paddle to 28 wpm did not ask for it to change because a macro went out at 25.
And there is no backspace: TCI can stop a message but cannot un-type one, so the
type-ahead correction the Flex engine offers is absent rather than faked.

internal/cat/tci_test.go

@@ -22,3 +22,20 @@ func TestTCISpotsUnsupported(t *testing.T) {
 		}
 	}
 }
+
+func TestSanitiseTCICW(t *testing.T) {
+	// The separators must never survive: a comma would become another argument
+	// and a semicolon would end the command with the message half sent.
+	for _, c := range []struct{ in, want string }{
+		{"cq cq de f4bpo", "CQ CQ DE F4BPO"},
+		{" tu 599 ", "TU 599"},
+		{"73, gl", "73  GL"},
+		{"test;cw_macros_stop", "TEST CW_MACROS_STOP"},
+		{"line\r\nbreak", "LINE  BREAK"},
+		{"   ", ""},
+	} {
+		if got := sanitiseTCICW(c.in); got != c.want {
+			t.Errorf("sanitiseTCICW(%q) = %q, want %q", c.in, got, c.want)
+		}
+	}
+}