Upgrade live timing page for race weekends

- Track status flag banner (green/yellow/SC/VSC/red, defensive mapping)
- Weather strip: air/track temp, humidity, wind with compass, rain badge
- Gap trend sparklines from a per-driver interval ring buffer
- Battle detection: consecutive cars within 1.0s chained and highlighted
- Stint history column with compound sequence per driver
- Pinnable drivers (max 3) with focus cards, persisted to localStorage

Pure logic lives in lib/gapHistory.ts and lib/battles.ts with unit
tests; 137 frontend tests passing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/live/StintHistory.tsx

@@ -0,0 +1,29 @@
+import type { LiveStintData } from '../../types'
+import { compoundClass, compoundLetter } from '../../lib/live'
+
+interface Props {
+  stints: LiveStintData[] | undefined
+}
+
+export function StintHistory({ stints }: Props) {
+  if (!stints || stints.length === 0) {
+    return <span className="stint-empty">-</span>
+  }
+
+  return (
+    <span className="stint-seq" data-testid="stint-seq">
+      {stints.map((stint, index) => (
+        <span className="stint-item" key={index}>
+          {index > 0 && <span className="stint-arrow">›</span>}
+          <span
+            className={`stint-dot ${compoundClass(stint.Compound)}`}
+            title={`${stint.Compound || 'Unknown'}${stint.New ? ' (new)' : ''} · ${stint.Laps} laps`}
+          >
+            {compoundLetter(stint.Compound)}
+          </span>
+          {stint.Laps > 0 && <span className="stint-laps">{stint.Laps}</span>}
+        </span>
+      ))}
+    </span>
+  )
+}