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_cw.go

@@ -0,0 +1,72 @@
+package cat
+
+import (
+	"fmt"
+	"strings"
+)
+
+// CW keying over TCI — a sixth CW engine, so a SunSDR needs no WinKeyer and no
+// second serial port: the radio's own macro keyer is driven over the WebSocket
+// that already carries the CAT.
+//
+// The commands, from the TCI command table (confirmed against ars-ka0s/eesdr-tci,
+// the same source that settled SPOT):
+//
+//	CW_MACROS:<trx>,<text>;   send text through the radio's keyer
+//	CW_MACROS_SPEED:<wpm>;    the speed those macros are keyed at
+//	CW_MACROS_STOP;           abort what is being keyed
+//	CW_MACROS_EMPTY;          the radio saying the buffer has run dry
+//
+// CW_MSG (TCI 2.0) does the same with separate before/after callsign fields.
+// CW_MACROS is used instead because it exists from 1.6 and OpsLog resolves the
+// variables itself — the text handed here is already what should go on the air.
+//
+// Notably absent: there is no backspace. The FlexRadio CWX keyer can un-type
+// what has not been sent yet; TCI can only stop. So the type-ahead correction
+// the Flex engine offers is not offered here rather than faked.
+
+// tciCWTextLimit caps one macro. A runaway paste down a WebSocket that also
+// carries audio is worth refusing, and no real CW message is this long.
+const tciCWTextLimit = 512
+
+// SendCW keys a message through the radio's macro keyer.
+func (t *TCI) SendCW(text string) error {
+	msg := sanitiseTCICW(text)
+	if msg == "" {
+		return nil
+	}
+	return t.send(fmt.Sprintf("cw_macros:0,%s;", msg))
+}
+
+// StopCW aborts the message being keyed.
+func (t *TCI) StopCW() error { return t.send("cw_macros_stop;") }
+
+// SetCWSpeed sets the macro keyer speed in words per minute.
+//
+// Only the MACRO speed: the paddle keyer has its own (CW_KEYER_SPEED) and an
+// operator who has set their paddle to 28 wpm did not ask the logger to change
+// it because a macro went out at 25.
+func (t *TCI) SetCWSpeed(wpm int) error {
+	if wpm < 5 {
+		wpm = 5
+	}
+	if wpm > 60 {
+		wpm = 60
+	}
+	return t.send(fmt.Sprintf("cw_macros_speed:%d;", wpm))
+}
+
+// sanitiseTCICW makes a message safe to put in a TCI command.
+//
+// Commas and semicolons are the protocol's own separators — a comma inside the
+// text would be read as another argument and a semicolon would end the command
+// early, keying half a message and leaving the rest to be parsed as a command of
+// its own. Neither belongs in Morse anyway.
+func sanitiseTCICW(text string) string {
+	s := strings.ToUpper(strings.TrimSpace(text))
+	s = strings.NewReplacer(",", " ", ";", " ", "\r", " ", "\n", " ").Replace(s)
+	if len(s) > tciCWTextLimit {
+		s = s[:tciCWTextLimit]
+	}
+	return strings.TrimSpace(s)
+}