feat(dvk): key the DATA input, not the microphone

From a TS-590SG report: the voice keyer played through the rig's USB
codec and the radio transmitted silence. Its manual says why — 'TX P1,
0: SEND (normal transmission using the MIC input), 1: DATA SEND
(ACC2/USB input)' — and OpsLog only ever sent the bare TX, so the radio
dutifully opened a front microphone nobody was speaking into.

An option on the audio page, shown for CAT keying, says where the
keyer's audio actually arrives; the manager routes it to a backend that
draws the distinction and falls back to the ordinary key for every rig
where one PTT is all there is. Test PTT goes down the same path, so it
tests what will happen rather than something adjacent.

frontend/wailsjs/go/models.ts

@@ -1924,6 +1924,7 @@ export namespace main {
 	    preroll_seconds: number;
 	    ptt_method: string;
 	    ptt_port: string;
+	    ptt_data: boolean;
 	    format: string;
 	    from_gain: number;
 	    mic_gain: number;
@@ -1945,6 +1946,7 @@ export namespace main {
 	        this.preroll_seconds = source["preroll_seconds"];
 	        this.ptt_method = source["ptt_method"];
 	        this.ptt_port = source["ptt_port"];
+	        this.ptt_data = source["ptt_data"];
 	        this.format = source["format"];
 	        this.from_gain = source["from_gain"];
 	        this.mic_gain = source["mic_gain"];