feat: realtime Live dashboard in Data Explorer + fix panel layout

- New "Live" tab: auto-polls /api/federated/live every 2.5s with
  animated counters, ingestion throughput sparkline, per-source
  write-rate bars, a region scorecard matrix (heat-shaded) and live
  business breakdown charts (region/channel/status/customers/
  telemetry/supply)
- Backend /api/federated/live: instant source estimates (Postgres),
  monotonic max(event_id) for MySQL and Mongo estimated count for
  immediate movement, Cassandra from cached matrix; business aggs
  cached over the small Hadoop lake tables (short TTL)
- Fix embedded Trino panels being squeezed with internal scrollbars
  by making panels/grids shrink-0 so the page scrolls instead

ui/src/components/features/DataExplorerView.tsx

@@ -15,15 +15,18 @@ import {
   Network,
   HardDrive,
   ShieldCheck,
+  Radio,
 } from 'lucide-react'
 import { cn } from '../../lib/utils'
 import { TrinoFederationView, type SubTab } from './TrinoFederationView'
+import { LiveDashboard } from './LiveDashboard'
 
-type ExplorerTab = 'business' | SubTab
+type ExplorerTab = 'business' | 'live' | SubTab
 
-const TABS: { id: ExplorerTab; label: string; icon: typeof Users; hint: string }[] = [
+const TABS: { id: ExplorerTab; label: string; icon: typeof Users; hint: string; live?: boolean }[] = [
   { id: 'business', label: 'Business Overview', icon: BarChart3, hint: 'Customers, orders, workforce, supply chain & telemetry across every source' },
-  { id: 'federated', label: 'Federated (Trino)', icon: Network, hint: 'One SQL engine joining PostgreSQL, MySQL & MongoDB live — region scorecard' },
+  { id: 'live', label: 'Live', icon: Radio, hint: 'Realtime business activity — live counters, ingestion throughput & region matrix', live: true },
+  { id: 'federated', label: 'Federated (Trino)', icon: Network, hint: 'One SQL across all 5 databases + region scorecard joined live' },
   { id: 'lake', label: 'Hadoop Lake', icon: HardDrive, hint: 'All business data mirrored as external Iceberg tables on HDFS' },
   { id: 'dictionary', label: 'Data Dictionary', icon: ShieldCheck, hint: 'Every table & column with PII / masking status — exactly what the assistant sees' },
 ]
@@ -263,7 +266,7 @@ export function DataExplorerView() {
 
       {/* tab bar */}
       <div className="flex shrink-0 flex-wrap gap-1 px-1">
-        {TABS.map(({ id, label, icon: Icon }) => (
+        {TABS.map(({ id, label, icon: Icon, live }) => (
           <button
             key={id}
             type="button"
@@ -273,13 +276,24 @@ export function DataExplorerView() {
               view === id ? 'bg-docker/15 text-docker' : 'text-foreground-muted hover:bg-surface-overlay',
             )}
           >
-            <Icon className="h-3.5 w-3.5" /> {label}
+            {live ? (
+              <span className="relative flex h-2 w-2">
+                <span className="absolute inline-flex h-full w-full animate-ping rounded-full bg-emerald-400 opacity-75" />
+                <span className="relative inline-flex h-2 w-2 rounded-full bg-emerald-400" />
+              </span>
+            ) : (
+              <Icon className="h-3.5 w-3.5" />
+            )}
+            {label}
           </button>
         ))}
       </div>
 
+      {/* Live realtime dashboard */}
+      {view === 'live' && <LiveDashboard />}
+
       {/* Trino federation / lake / dictionary tabs */}
-      {view !== 'business' && <TrinoFederationView embedded activeTab={view} />}
+      {(view === 'federated' || view === 'lake' || view === 'dictionary') && <TrinoFederationView embedded activeTab={view} />}
 
       {/* ───────── BUSINESS OVERVIEW ───────── */}
       {view === 'business' && (