feat(radio): answer the internet radio controls through the radio store

The Radio panel's and Cockpit's Enable, launcher, station tag,
transport and volume controls call RadioControls through the radio
store instead of DOM listeners. A refused station tag gets the kept tag
back from act(), which now returns what the answering action returned.
The Cockpit's station steps keep rotate: false. The unused element
fields go from the shell.

src/ui/radioPanelActions.test.mjs

@@ -0,0 +1,80 @@
+// src/ui/radioPanelActions.test.mjs — the Radio panel's controls call
+// RadioControls through the radio store, and a refused station tag puts the
+// select back on the tag the directory keeps.
+import '../testSupport/registerDom.mjs';
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createApp } from 'vue';
+import { createPinia } from 'pinia';
+import { useRadioStore } from './stores/radio.js';
+import RadioPanel from './views/panels/RadioPanel.vue';
+
+function mount(t, { filter = (tag) => tag } = {}) {
+  document.body.replaceChildren();
+  const pinia = createPinia();
+  const calls = [];
+  useRadioStore(pinia).connect(
+    new Proxy(
+      {},
+      {
+        get:
+          (_, name) =>
+          (...args) => {
+            calls.push([name, ...args]);
+            return name === 'setRadioFilter' ? filter(...args) : undefined;
+          },
+      },
+    ),
+  );
+  const app = createApp(RadioPanel).use(pinia);
+  app.mount(document.body.appendChild(document.createElement('div')));
+  t.after(() => app.unmount());
+  return calls;
+}
+const $ = (id) => document.getElementById(id);
+const pickTag = (tag) => {
+  const select = $('radio-filter');
+  select.disabled = false;
+  const option = document.createElement('option');
+  option.value = tag;
+  select.append(option);
+  select.value = tag;
+  select.dispatchEvent(new Event('change', { bubbles: true }));
+  return select.value;
+};
+
+test('the panel’s Enable, transport and volume call RadioControls', (t) => {
+  const calls = mount(t);
+  for (const id of [
+    'radio-enable-btn',
+    'radio-prev-btn',
+    'radio-play-btn',
+    'radio-next-btn',
+    'radio-stop-btn',
+  ]) {
+    $(id).disabled = false;
+    $(id).click();
+  }
+  $('radio-volume').disabled = false;
+  $('radio-volume').value = '35';
+  $('radio-volume').dispatchEvent(new Event('input', { bubbles: true }));
+  assert.deepEqual(calls, [
+    ['toggleRadio', 'panel'],
+    ['cycleRadio', -1],
+    ['toggleRadioPlayback'],
+    ['cycleRadio', 1],
+    ['stopRadio'],
+    ['setRadioVolume', '35'],
+  ]);
+});
+
+test('an accepted station tag stays picked', (t) => {
+  const calls = mount(t);
+  assert.equal(pickTag('jazz'), 'jazz');
+  assert.deepEqual(calls, [['setRadioFilter', 'jazz']]);
+});
+
+test('a refused station tag puts the select back on the kept tag', (t) => {
+  mount(t, { filter: () => 'all' });
+  assert.equal(pickTag('jazz'), 'all');
+});