Release Preview 20 shared desktop, Android and Sargo updates

Restore Gaia settings and media workflows, extend native network adapters, and align the APK payload. Generate French/English changelogs and website entries from the simplified JSON source.

Validation: shared JS and Tundra unit tests; desktop workflows and persistence; signed APK payload parity; Sargo RAM and installed startup with boot readback. Android runtime qualification is recorded separately.

host/gaia-theme.js

@@ -0,0 +1,58 @@
+// Shared appearance preference; external browser pages are not injected.
+(() => {
+  const key = 'vulpes.theme';
+  const system = matchMedia('(prefers-color-scheme: dark)');
+  let mode = 'light', select;
+  function apply(value) {
+    mode = ['light', 'dark', 'system'].includes(value) ? value : 'light';
+    document.documentElement.dataset.vulpesTheme =
+      mode === 'system' ? (system.matches ? 'dark' : 'light') : mode;
+    if (select) select.value = mode;
+  }
+  system.addEventListener('change', () => apply(mode));
+  addEventListener('vulpes-service-event', ({detail}) => {
+    if (detail.type === 'settingchange' && detail.data.key === key) apply(detail.data.value);
+  });
+  VulpesCompat.call('appearance.current', {}).then(apply).catch(console.error);
+
+  if (location.hostname !== 'settings.localhost') return;
+  function label() {
+    const lang = document.documentElement.lang || navigator.language;
+    const labels = lang.startsWith('fr') ? ['Apparence', 'Clair', 'Sombre', 'Selon le système'] :
+      lang.startsWith('el') ? ['Εμφάνιση', 'Φωτεινό', 'Σκοτεινό', 'Σύμφωνα με το σύστημα'] :
+      ['Appearance', 'Light', 'Dark', 'Follow system'];
+    const title = document.getElementById('vulpes-theme-label');
+    if (title && title.textContent !== labels[0]) title.textContent = labels[0];
+    if (select) [...select.options].forEach((option, i) => {
+      if (option.textContent !== labels[i + 1]) option.textContent = labels[i + 1];
+    });
+  }
+  function insert() {
+    const list = document.querySelector('#display > div > ul');
+    if (!list || select?.isConnected) return;
+    const row = document.createElement('li'), title = document.createElement('p');
+    row.id = 'vulpes-theme-row';
+    title.id = 'vulpes-theme-label';
+    const wrapper = document.createElement('span');
+    wrapper.className = 'button icon icon-dialog';
+    select = document.createElement('select');
+    select.id = 'vulpes-theme';
+    select.setAttribute('aria-labelledby', title.id);
+    for (const value of ['light', 'dark', 'system']) {
+      const option = document.createElement('option');
+      option.value = value; select.append(option);
+    }
+    select.value = mode;
+    select.onchange = async () => {
+      select.disabled = true;
+      try { await navigator.mozSettings.createLock().set({[key]:select.value}); }
+      catch (error) { select.value = mode; console.error(error); }
+      finally { select.disabled = false; }
+    };
+    wrapper.append(select); row.append(title, wrapper); list.append(row); label();
+  }
+  addEventListener('localized', label);
+  new MutationObserver(() => { insert(); label(); }).observe(document.documentElement,
+    {childList:true, subtree:true, attributes:true, attributeFilter:['lang']});
+  insert();
+})();