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