fix(ui): faster bitcoin sync refresh + unstick ElectrumX loader (B15,B7)

B15: Home system stats (incl. bitcoin sync %) polled every 30s — too slow;
now 10s so sync progress tracks the actual block height more closely.

B7: the ElectrumX sync overlay was gated only on status!=='synced', so if
the status never flips to 'synced' (ElectrumX stale/disconnected) the loader
stuck on top forever. Now the overlay hides and the app iframe loads when
the sync status is stale (fail-open), while still showing during active
indexing. type-check EXIT 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/src/views/Home.vue

@@ -482,7 +482,7 @@ const cloudFolderDisplay = computed(() => cloudFolderCount.value !== null ? Stri
 
 onMounted(async () => {
   try { const usage = await fileBrowserClient.getUsage(); cloudStorageUsed.value = usage.totalSize; cloudFolderCount.value = usage.folderCount } catch { /* not running */ }
-  loadSystemStats(); systemStatsInterval = setInterval(loadSystemStats, 30000); checkUpdateStatus(); loadWeb5Status()
+  loadSystemStats(); systemStatsInterval = setInterval(loadSystemStats, 10000); checkUpdateStatus(); loadWeb5Status()
 })
 
 // Wallet modals

neode-ui/src/views/appSession/AppSessionFrame.vue

@@ -13,7 +13,10 @@
          index is still being built (the Electrum server can't serve clients
          until then). Mirrors the Fedimint Guardian "wait page" design. -->
     <Transition name="content-fade">
-      <div v-if="electrsSync" class="absolute inset-0 z-10 flex flex-col items-center justify-center">
+      <!-- Sync overlay only while ElectrumX is actively indexing. If the status
+           goes stale (ElectrumX disconnected/unresponsive) we stop blocking and
+           let the app's own UI load instead of a loader stuck on top (B7). -->
+      <div v-if="electrsSync && !electrsSync.stale" class="absolute inset-0 z-10 flex flex-col items-center justify-center">
         <div class="text-center px-8 w-full max-w-md">
           <div class="w-16 h-16 mx-auto mb-4 rounded-2xl bg-white/5 border border-white/10 flex items-center justify-center">
             <svg class="w-8 h-8 text-orange-300 animate-pulse" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -42,7 +45,7 @@
     </Transition>
 
     <div
-      v-if="appUrl && !iframeBlocked && !electrsSync"
+      v-if="appUrl && !iframeBlocked && (!electrsSync || electrsSync.stale)"
       class="absolute inset-0 app-session-frame-scroll-host"
       tabindex="-1"
       @pointerdown="focusIframe"