feat(ui): add compact KPI metrics in tab bar (Total, Err%, Avg, P99)

New TabKpis component shows scope-aware metrics with trend arrows
aligned right in the content tab bar. Each metric shows current value
and an arrow indicating change vs previous period (green=good, red=bad).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/ContentTabs.tsx

@@ -1,5 +1,6 @@
 import { Tabs } from '@cameleer/design-system';
-import type { TabKey } from '../hooks/useScope';
+import type { TabKey, Scope } from '../hooks/useScope';
+import { TabKpis } from './TabKpis';
 import styles from './ContentTabs.module.css';
 
 const TABS = [
@@ -11,9 +12,10 @@ const TABS = [
 interface ContentTabsProps {
   active: TabKey;
   onChange: (tab: TabKey) => void;
+  scope: Scope;
 }
 
-export function ContentTabs({ active, onChange }: ContentTabsProps) {
+export function ContentTabs({ active, onChange, scope }: ContentTabsProps) {
   return (
     <div className={styles.wrapper}>
       <Tabs
@@ -21,6 +23,7 @@ export function ContentTabs({ active, onChange }: ContentTabsProps) {
         active={active}
         onChange={(v) => onChange(v as TabKey)}
       />
+      <TabKpis scope={scope} />
     </div>
   );
 }