feat(dashboard): version loading indicator + immediate first poll (#181)

* feat(dashboard): show version loading indicator and fire poll immediately

- Show "Verificando..." while /api/version resolves on first load
- Fire first version poll immediately instead of waiting 15s
- Fallback to "-" when version is unavailable

* i18n: localize the version-check loading label

The sidebar version indicator hard-coded the Spanish string 'Verificando...',
shipping it to every user regardless of locale. Route it through i18n instead:
new 'common.checking' key (en: 'Checking...', es: 'Verificando...'); all other
locales fall back to the English canonical, matching the rest of the UI.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: ScreenTinker <hello@screentinker.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

frontend/js/app.js

@@ -570,10 +570,15 @@ let knownHash = null;
 export function updateVersionIndicator({ version, latest_version, update_available }) {
   const label = document.getElementById('versionLabel');
   const badge = document.getElementById('versionBadge');
-  if (label) label.textContent = version ? 'v' + version : '';
+  if (label) label.textContent = version ? 'v' + version : '-';
   if (badge) badge.hidden = !update_available;
 }
-setInterval(async () => {
+
+// Show loading state while first poll resolves
+const verLabel = document.getElementById('versionLabel');
+if (verLabel) verLabel.textContent = t('common.checking');
+
+async function checkVersion() {
   try {
     const res = await fetch('/api/version');
     const data = await res.json();
@@ -590,7 +595,9 @@ setInterval(async () => {
     }
     updateVersionIndicator(data);
   } catch {}
-}, 15000);
+}
+checkVersion(); // Fire first poll immediately
+setInterval(checkVersion, 15000);
 
 // Session timeout warning - check JWT expiry every minute
 if (isAuthenticated()) {

frontend/js/i18n/en.js

@@ -35,6 +35,7 @@ export default {
   'common.saving': 'Saving...',
   'common.deleting': 'Deleting...',
   'common.loading': 'Loading...',
+  'common.checking': 'Checking...',
   'confirm_delete.type_label': 'Type "{name}" to confirm',
   'confirm_delete.failed': 'Action failed',
   'common.connected': 'Connected',

frontend/js/i18n/es.js

@@ -31,6 +31,7 @@ export default {
   'common.edit': 'Editar',
   'common.done': 'Listo',
   'common.loading': 'Cargando...',
+  'common.checking': 'Verificando...',
   'common.connected': 'Conectado',
   'common.disconnected': 'Desconectado',
   'common.never': 'Nunca',