fix(antenna): pick the SteppIR's serial port from a list

The COM port was a bare text field — the only serial device in the app without
a port list, and typing one by hand gave no clue when it failed.

A Combobox rather than the Select the other devices use, deliberately: the port
of a USB adapter that is not plugged in does not appear in any list, and
refusing a typed value would mean the antenna cannot be configured until the
adapter is in. Detected ports are offered, anything else is still accepted, and
the value is trimmed and upper-cased on the way in.

The failure itself was already logged by the SteppIR client ("cannot open COM7
@ 4800 baud"); what was missing was the line above it not claiming the antenna
had connected. That is fixed separately.

Carries the 0.26.2 changelog entries for this and the three preceding commits —
one file, and splitting it four ways would have said less than this does.

frontend/src/components/SettingsModal.tsx

@@ -68,6 +68,7 @@ import {
 import { WebPublishPanel } from '@/components/WebPublishPanel';
 import { Button } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
+import { Combobox } from '@/components/ui/combobox';
 import { Label } from '@/components/ui/label';
 import { Textarea } from '@/components/ui/textarea';
 import { Checkbox } from '@/components/ui/checkbox';
@@ -3458,12 +3459,25 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
             <div className="grid grid-cols-3 gap-3">
               <div className="space-y-1 col-span-2">
                 <Label>{t('hw.motorCom')}</Label>
-                <Input
-                  value={ultrabeam.com ?? ''}
-                  onChange={(e) => setUltrabeam((s) => ({ ...s, com: e.target.value }))}
-                  placeholder="COM3"
-                  className="font-mono"
-                />
+                {/* A list AND a text field, which is why this is a Combobox and
+                    not the Select the other serial devices use: the port for a
+                    USB adapter that is currently unplugged does not appear in
+                    the list, and refusing to accept it typed means the antenna
+                    cannot be configured until the adapter is in. The detected
+                    ports are offered; anything else is still accepted. */}
+                <div className="flex items-center gap-1">
+                  <Combobox
+                    value={ultrabeam.com ?? ''}
+                    options={wkPorts}
+                    allowFreeText
+                    commitOnType
+                    placeholder="COM3"
+                    className="font-mono flex-1"
+                    onChange={(v) => setUltrabeam((s) => ({ ...s, com: v.trim().toUpperCase() }))}
+                  />
+                  <Button type="button" variant="outline" size="sm" className="shrink-0"
+                    onClick={() => ListSerialPorts().then((ps) => setWkPorts((ps ?? []) as string[])).catch(() => {})}>↻</Button>
+                </div>
               </div>
               <div className="space-y-1">
                 <Label>{t('hw.motorBaud')}</Label>