feat(portal): wire DashboardPage to live Chain-138 RPC + SolaceScan Explorer

- Add services/{http,chain138,explorer,proxmox,dbisCore} + hooks/{useLiveChain,useOnChainBalances}
- Add BackendStatusBar + LiveNetworkPanel components on DashboardPage
- Overlay on-chain META balance on account rows carrying a walletAddress
- Normalize EIP-55 checksum in chain138.getNativeBalance so hand-typed
  sample custody addresses (e.g. 0x742d35Cc...bD38) don't silently drop
  out of the balance map
- Default RPC: https://rpc.d-bis.org (user-preferred gateway)
- proxmox.ts stays mocked (CF-Access, needs BFF); dbisCore.ts stays
  mocked (no public deployment yet)

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

src/services/explorer.ts

@@ -0,0 +1,82 @@
+/**
+ * SolaceScan Explorer (Blockscout v2) client for Chain 138.
+ *
+ * Base URL: https://api.explorer.d-bis.org (CORS *)
+ * Fallback: https://explorer.d-bis.org/api/v2 (same data, different host)
+ *
+ * We hit the `api.*` subdomain by default because it returns clean JSON
+ * without the Next.js HTML wrapper.
+ */
+
+import { httpJson } from './http';
+import { endpoints } from '../config/endpoints';
+
+const api = (path: string) => `${endpoints.explorer.apiBaseUrl}/api/v2${path}`;
+
+export interface ExplorerStats {
+  total_blocks: number;
+  total_transactions: number;
+  total_addresses: number;
+  latest_block: number;
+  average_block_time: number;
+  gas_prices: { average: number; fast?: number; slow?: number };
+  network_utilization_percentage: number;
+  transactions_today: number;
+}
+
+export async function getExplorerStats(): Promise<ExplorerStats> {
+  return httpJson<ExplorerStats>(api('/stats'));
+}
+
+export interface ExplorerBlock {
+  height: number;
+  hash: string;
+  timestamp: string;
+  tx_count: number;
+  gas_used: string;
+  gas_limit: string;
+  size: number;
+  miner: { hash: string };
+}
+
+export async function getLatestBlocks(): Promise<ExplorerBlock[]> {
+  return httpJson<ExplorerBlock[]>(api('/main-page/blocks'));
+}
+
+export interface ExplorerTx {
+  hash: string;
+  block_number: number;
+  timestamp: string;
+  from: { hash: string };
+  to: { hash: string } | null;
+  value: string; // wei
+  gas_used: string;
+  gas_price: string;
+  status: 'ok' | 'error' | null;
+  method: string | null;
+  fee: { value: string };
+}
+
+interface PagedTxResponse { items: ExplorerTx[]; next_page_params?: unknown }
+
+export async function getLatestTransactions(limit = 20): Promise<ExplorerTx[]> {
+  const data = await httpJson<PagedTxResponse>(api('/transactions'));
+  return (data.items ?? []).slice(0, limit);
+}
+
+export async function getAddressTransactions(address: string, limit = 20): Promise<ExplorerTx[]> {
+  const data = await httpJson<PagedTxResponse>(api(`/addresses/${address}/transactions`));
+  return (data.items ?? []).slice(0, limit);
+}
+
+export function explorerTxUrl(hash: string): string {
+  return `${endpoints.explorer.baseUrl}/tx/${hash}`;
+}
+
+export function explorerAddressUrl(address: string): string {
+  return `${endpoints.explorer.baseUrl}/address/${address}`;
+}
+
+export function explorerBlockUrl(height: number): string {
+  return `${endpoints.explorer.baseUrl}/block/${height}`;
+}