feat(station): drive the motorized antenna from its widget

It showed pattern, elements and Retract — everything except where the antenna
is pointed, which is the thing an operator changes most. Tuning it meant opening
Settings or moving the rig.

A button per band, taken from the bands configured in Settings rather than a
list invented here: a band dropped there cannot be clicked here. They point at
where people actually work, not the arithmetic centre — 20 m centres on 14175
and nobody lives there, 10 m spans 1.7 MHz of which the top half is empty.

Up and down move 25 kHz, which is also the finest tracking threshold: a smaller
nudge would be undone by the next poll while tracking is on. They work from the
ANTENNA's frequency, not the rig's, or walking the antenna across a band while
the rig stays put would be undone on the first press.

Tracking moved within reach because it is an operating decision — off to park
the antenna, on to resume — not something set up once. Its step only appears
when it is on: a threshold for something switched off is a question the operator
cannot act on.

MotorTuneKHz carries the CURRENT direction rather than resetting it. Both
controllers set frequency and pattern in one command, so a bare frequency would
silently drop a 180° or bidirectional pattern — a beam turning round is not an
acceptable side effect of clicking a band.

frontend/wailsjs/go/models.ts

@@ -3300,6 +3300,9 @@ export namespace main {
 	    band: number;
 	    moving: boolean;
 	    elements: number[];
+	    follow: boolean;
+	    step_khz: number;
+	    bands: string[];
 	
 	    static createFrom(source: any = {}) {
 	        return new UltrabeamStatusInfo(source);
@@ -3315,6 +3318,9 @@ export namespace main {
 	        this.band = source["band"];
 	        this.moving = source["moving"];
 	        this.elements = source["elements"];
+	        this.follow = source["follow"];
+	        this.step_khz = source["step_khz"];
+	        this.bands = source["bands"];
 	    }
 	}
 	export class UpdateInfo {