feat: Yaesu control panel (meters, bands, DSP, TX), and drop a stale Flex hint

A console pane for the native Yaesu backend, in the same shape as the Icom and
Flex ones: S/PO/SWR meters, band and mode rows, AF/RF/squelch, AGC, the IPO/AMP1/
AMP2 front-end selector, ATT, NB, DNR + level, narrow filter, power in watts, mic
gain, VOX, split and ATU tune.

Three decisions worth keeping:

Panel reads are STAGGERED and live in their own file, away from ReadState. Meters
poll every cycle; settings only change when someone turns a knob, so they refresh
every 8th cycle and right after any set. Polling all of it every cycle would put
twenty queries a second on the serial link the frequency display shares.

Band buttons use the rig's own band memory (BS) rather than a frequency we pick,
so 20 m lands where the operator last was on 20 m — what the radio's own band
keys do.

A set is followed by a read-back, so the panel shows what the RIG ended up with,
not what we asked for; the two differ whenever a value is out of range or the
mode forbids the control. And a control the model lacks keeps its previous value
instead of dropping to zero, which reads as a setting that reset itself.

The S9 point of the S-meter scale is a hypothesis (the manual does not state it)
and is commented as such — one number to correct if reports come out an S unit
off, rather than a fudge spread through the RST helper.

Also removes the FlexRadio settings blurb, which explained the backend to
someone who had already chosen it.

frontend/wailsjs/go/models.ts

@@ -1074,6 +1074,58 @@ export namespace cat {
 	        this.fixed = source["fixed"];
 	    }
 	}
+	export class YaesuTXState {
+	    available: boolean;
+	    model?: string;
+	    mode?: string;
+	    transmitting: boolean;
+	    split: boolean;
+	    s_meter: number;
+	    power_meter: number;
+	    swr_meter: number;
+	    rf_power: number;
+	    mic_gain: number;
+	    af_gain: number;
+	    rf_gain: number;
+	    squelch: number;
+	    agc?: string;
+	    preamp: number;
+	    att: number;
+	    nb: boolean;
+	    nr: boolean;
+	    nr_level: number;
+	    narrow: boolean;
+	    vox: boolean;
+	
+	    static createFrom(source: any = {}) {
+	        return new YaesuTXState(source);
+	    }
+	
+	    constructor(source: any = {}) {
+	        if ('string' === typeof source) source = JSON.parse(source);
+	        this.available = source["available"];
+	        this.model = source["model"];
+	        this.mode = source["mode"];
+	        this.transmitting = source["transmitting"];
+	        this.split = source["split"];
+	        this.s_meter = source["s_meter"];
+	        this.power_meter = source["power_meter"];
+	        this.swr_meter = source["swr_meter"];
+	        this.rf_power = source["rf_power"];
+	        this.mic_gain = source["mic_gain"];
+	        this.af_gain = source["af_gain"];
+	        this.rf_gain = source["rf_gain"];
+	        this.squelch = source["squelch"];
+	        this.agc = source["agc"];
+	        this.preamp = source["preamp"];
+	        this.att = source["att"];
+	        this.nb = source["nb"];
+	        this.nr = source["nr"];
+	        this.nr_level = source["nr_level"];
+	        this.narrow = source["narrow"];
+	        this.vox = source["vox"];
+	    }
+	}
 
 }