fix(portal/reporting): normalize Blockscout avg_block_time ms->s

Blockscout /api/v2/stats returns average_block_time in milliseconds;
ReportingPage displays it as `${value.toFixed(1)}s` which rendered
~4424s instead of the real ~4.4s. Normalize in the service layer so
every caller gets seconds regardless of upstream format.

Co-Authored-By: Nakamoto, S <defi@defi-oracle.io>

src/services/explorer.ts

@@ -25,7 +25,15 @@ export interface ExplorerStats {
 }
 
 export async function getExplorerStats(): Promise<ExplorerStats> {
-  return httpJson<ExplorerStats>(api('/stats'));
+  const raw = await httpJson<ExplorerStats>(api('/stats'));
+  // Blockscout returns `average_block_time` in milliseconds; normalize to seconds
+  // so callers can display `${value.toFixed(1)}s` directly. Chain-138 block time
+  // is ~4s, so a raw value > 60 is a reliable signal that it is still in ms.
+  const average_block_time =
+    typeof raw.average_block_time === 'number' && raw.average_block_time > 60
+      ? raw.average_block_time / 1000
+      : raw.average_block_time;
+  return { ...raw, average_block_time };
 }
 
 export interface ExplorerBlock {