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/BattleChips.tsx

@@ -0,0 +1,21 @@
+import type { Battle } from '../../lib/battles'
+import { battleLabel } from '../../lib/battles'
+
+interface Props {
+  battles: Battle[]
+}
+
+export function BattleChips({ battles }: Props) {
+  if (battles.length === 0) return null
+
+  return (
+    <div className="battle-chips" data-testid="battle-chips">
+      <span className="battle-chips-label">Battles</span>
+      {battles.map((battle) => (
+        <span className="battle-chip mono" key={battle.drivers.map((d) => d.racingNumber).join('-')}>
+          {battleLabel(battle)}
+        </span>
+      ))}
+    </div>
+  )
+}