feat(update): unify the updater with Sabiá's Gitea-based mechanism

Replaces the signed tauri-plugin-updater (latest.json manifest, minisign
key pair) with the same simple mechanism Sabiá already uses: query the
Gitea Releases API directly, download the matching platform archive,
verify its SHA-256 checksum, and swap the binary in place. The CI job
that built the old latest.json manifest is removed in the next commit,
alongside an unrelated runner-routing change to the same workflow file.

- New guara-core::update module (check/apply), ported from
  sabia-core::update and adapted to Guará's own release asset naming
  (guara-<tag>-<platform>.tar.gz, matching scripts/package-cli.sh).
- New Engine::update_check / Engine::update_apply, wired into the RPC
  service for the browser UI.
- New CLI subcommand: "guara update" (check) and "guara update --apply"
  (download, verify, replace), mirroring "sabia update".
- GUI: replaced the Tauri plugin-updater flow (download_and_install,
  update-progress events, in-app restart) with a call to the new
  update_check/update_apply commands. The desktop app can no longer
  self-install in one click — it now points the user to the Releases
  page, same as Sabiá's desktop app already does.
- Removed tauri-plugin-updater, createUpdaterArtifacts and the
  updater.pubkey config, the signing-key loading in build-gui.sh, the
  CI step testing the old latest.json generator, and the now-unused
  make-latest-json.py/test_make_latest_json.py scripts.
- Documented the break for existing installs in CHANGELOG.md /
  CHANGELOG.pt-BR.md: versions up to 1.3.2 won't find this release
  automatically and need one manual download.

Trade-off accepted knowingly: SHA-256 verifies integrity against
Gitea's own API but, unlike the retired signed mechanism, does not
protect against a compromised Gitea server independently of it. This
is Lucas's own self-hosted instance, not a third-party mirror.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VAyr8d7HuAdUGB6aA5xmDD

apps/gui/ui/app.js

@@ -765,61 +765,47 @@ $('#settingsBtn')?.addEventListener('click', () => {
 });
 
 // ------------------------------------------------------------------ app updater
-// The desktop shell (Tauri) queries `latest.json` from the Gitea release, verifies the
-// package signature against the embedded public key, installs, and relaunches. No-op in browser mode (`guara ui`).
+// The desktop shell (Tauri) queries Gitea Releases API and notifies the user.
+// No-op in browser mode (`guara ui`).
 let UPD = null;
 
 async function checkUpdate(manual) {
   if (!tauri?.core?.invoke) return;
+  const updNow = $('#updNow');
+  if (updNow) updNow.textContent = 'checando…';
   try {
-    UPD = await tauri.core.invoke('update_check');
-    renderUpdateCard();
-    if (manual) toast(UPD ? `Nova versão ${UPD.version} disponível` : 'Você já está na versão mais recente');
+    const status = await tauri.core.invoke('update_check');
+    if (status?.update_available) {
+      UPD = {
+        current: status.current_version,
+        version: status.latest_version,
+        url: 'https://git.lucasrguerra.dev.br/lucasrguerra/guara/releases',
+      };
+      renderUpdateCard();
+      if (updNow) updNow.textContent = `atualizar para ${status.latest_version}`;
+      if (manual) toast(`Nova versão ${status.latest_version} disponível`);
+    } else {
+      UPD = null;
+      renderUpdateCard();
+      if (updNow) updNow.textContent = 'já atualizado';
+      if (manual) toast('Você já está na versão mais recente');
+    }
   } catch (e) {
+    if (updNow) updNow.textContent = 'Verificar agora';
     if (manual) toast(`Não foi possível verificar atualizações: ${e}`);
   }
 }
 
-function renderUpdateCard(state) {
+function renderUpdateCard() {
   let el = $('#updateCard');
   if (!UPD) { el?.remove(); return; }
   if (!el) { el = document.createElement('div'); el.id = 'updateCard'; el.className = 'update-card'; el.setAttribute('role', 'status'); document.body.appendChild(el); }
-  if (state === 'busy') return;
   el.innerHTML = `<div class="upd-head"><b>Nova versão do Guará disponível</b><span class="mono upd-ver">v${esc(UPD.current)} → v${esc(UPD.version)}</span></div>
-    ${UPD.auto ? '' : '<p class="sub">Esta instalação vem de um pacote do sistema e não se atualiza sozinha. Baixe a versão nova na página da release:</p><p class="mono upd-url">' + esc(UPD.url) + '</p>'}
+    <p class="sub">Esta instalação vem de um pacote do sistema e não se atualiza sozinha. Baixe a versão nova na página da release:</p><p class="mono upd-url">${esc(UPD.url)}</p>
     <div class="upd-actions">
-      ${UPD.auto ? '<button class="btn primary sm" id="updGo">Atualizar agora</button>' : ''}
-      ${UPD.notes ? '<button class="btn sm" id="updNotes">Novidades</button>' : ''}
       <button class="btn sm" id="updLater">Depois</button>
     </div>`;
-  $('#updGo')?.addEventListener('click', installUpdate);
   $('#updLater')?.addEventListener('click', () => { UPD = null; el.remove(); });
-  $('#updNotes')?.addEventListener('click', () => info({ title: `Guará ${UPD.version}`, html: `<pre class="upd-notes">${esc(UPD.notes)}</pre>` }));
-}
-
-async function installUpdate() {
-  const el = $('#updateCard');
-  el.innerHTML = `<div class="upd-head"><b>Atualizando o Guará…</b></div>
-    <div class="bar indet" id="updBar"><i style="width:0"></i></div><p class="sub" id="updMsg">Baixando a atualização…</p>`;
-  renderUpdateCard('busy');
-  try {
-    await tauri.core.invoke('update_install');
-  } catch (e) {
-    toast(String(e));
-    renderUpdateCard();
-  }
-}
-
-function updateProgress(p) {
-  const bar = $('#updBar'); const msg = $('#updMsg');
-  if (!bar || !msg) return;
-  if (p.installing) { bar.classList.add('indet'); msg.textContent = 'Instalando… o Guará vai reabrir sozinho.'; return; }
-  if (p.total) {
-    const pct = Math.min(100, Math.round((p.downloaded / p.total) * 100));
-    bar.classList.remove('indet');
-    bar.firstElementChild.style.width = `${pct}%`;
-    msg.textContent = `Baixando… ${pct}%`;
-  }
 }
 
 // ------------------------------------------------------------------ close while scan is running
@@ -870,7 +856,6 @@ function watchClose() {
     setLang(SETTINGS.lang);
     if (SETTINGS.ui_lang !== currentLang()) saveSettings({ ui_lang: currentLang() });
     watchClose();
-    tauri?.event?.listen?.('update-progress', (e) => updateProgress(e.payload));
     if (SETTINGS.updates !== false) checkUpdate(false);
     if (tauri) S.elevated = await tauri.core.invoke('is_elevated').catch(() => true);
     tauri?.event?.listen?.('elevate-failed', (e) => { toast(String(e.payload || 'Não foi possível reiniciar como administrador')); });