feat(live): add web track map (#32)

Subscribe to SignalR Position.z and CarData.z, decode DEFLATE payloads, stream throttled positions over SSE, and render live car dots against cached track outline bounds with tap telemetry.

Alignment spike: no checked-in or locally cached real Position.z samples were available in this isolated worktree; verified both streams expose the official raw F1 X/Y/Z coordinate contract and implemented shared-bounds normalization against prefetched OpenF1 outlines. Fallback build-outline-from-stream was not taken.

Playwright remains out of scope for live rendering because BOXBOX_DISABLE_LIVE is used there; coverage is via parser, web handler/SSE, pure transform, and seeded component tests.

frontend/src/components/live/TrackMap.tsx

@@ -0,0 +1,145 @@
+import { useMemo, useState } from 'react'
+import type {
+  LiveDriverData,
+  LiveDriverInfo,
+  LivePosition,
+  LiveTelemetry,
+  TrackOutline,
+} from '../../types'
+import {
+  buildOutlinePath,
+  canvasToSvg,
+  isOnTrack,
+  normalizeRawPoint,
+} from '../../lib/trackmap'
+
+interface Props {
+  outline?: TrackOutline | null
+  positions: Record<string, LivePosition>
+  telemetry?: Record<string, LiveTelemetry>
+  drivers?: Record<string, LiveDriverData>
+  driverInfo?: Record<string, LiveDriverInfo>
+  loading?: boolean
+}
+
+export function TrackMap({
+  outline,
+  positions,
+  telemetry = {},
+  drivers = {},
+  driverInfo = {},
+  loading = false,
+}: Props) {
+  const [selected, setSelected] = useState<string | null>(null)
+  const outlinePath = useMemo(() => buildOutlinePath(outline?.points ?? []), [outline])
+  const cars = useMemo(() => {
+    if (!outline?.bounds) return []
+    return Object.entries(positions)
+      .map(([number, position]) => {
+        const canvas = normalizeRawPoint(position, outline.bounds)
+        return {
+          number,
+          position,
+          svg: canvasToSvg(canvas),
+          info: driverInfo[number],
+          driver: drivers[number],
+          telemetry: telemetry[number],
+          active: isOnTrack(position.status) && !drivers[number]?.Retired,
+        }
+      })
+      .sort((a, b) => Number(a.number) - Number(b.number))
+  }, [driverInfo, drivers, outline?.bounds, positions, telemetry])
+
+  const selectedCar = selected ? cars.find((car) => car.number === selected) : null
+
+  if (loading) {
+    return (
+      <section className="live-track-panel" data-testid="track-map">
+        <div className="sec-header">
+          <span className="sec-title">Track Map</span>
+        </div>
+        <div className="track-map-empty">loading cached circuit outline...</div>
+      </section>
+    )
+  }
+
+  if (!outline || !outlinePath) {
+    return (
+      <section className="live-track-panel" data-testid="track-map">
+        <div className="sec-header">
+          <span className="sec-title">Track Map</span>
+        </div>
+        <div className="track-map-empty">track outline unavailable for this live session</div>
+      </section>
+    )
+  }
+
+  return (
+    <section className="live-track-panel" data-testid="track-map">
+      <div className="sec-header">
+        <span className="sec-title">Track Map</span>
+        <span className="sec-meta">{cars.length ? `${cars.length} cars` : 'waiting for GPS'}</span>
+      </div>
+      <div className="track-map-stage">
+        <svg className="track-map-svg" viewBox="0 0 100 100" role="img" aria-label="Live track map">
+          <path className="track-map-outline-shadow" d={outlinePath} />
+          <path className="track-map-outline" d={outlinePath} />
+          {cars.map((car) => {
+            const label = car.info?.Tla || car.number
+            return (
+              <g
+                key={car.number}
+                role="button"
+                tabIndex={0}
+                aria-label={`${label} telemetry`}
+                className={`track-car ${car.active ? 'track-car-active' : 'track-car-inactive'} ${selected === car.number ? 'track-car-selected' : ''}`}
+                transform={`translate(${car.svg.x.toFixed(2)} ${car.svg.y.toFixed(2)})`}
+                onClick={() => setSelected(car.number)}
+                onKeyDown={(event) => {
+                  if (event.key === 'Enter' || event.key === ' ') {
+                    event.preventDefault()
+                    setSelected(car.number)
+                  }
+                }}
+              >
+                <circle r="2.8" fill={teamColor(car.info)} />
+                <text y="0.85">{label}</text>
+              </g>
+            )
+          })}
+        </svg>
+        {cars.length === 0 && <div className="track-map-empty track-map-overlay">waiting for live GPS</div>}
+        {selectedCar && (
+          <div className="track-telemetry" data-testid="track-telemetry">
+            <div className="track-telemetry-head">
+              <span className="track-driver-code">{selectedCar.info?.Tla || selectedCar.number}</span>
+              <span>{selectedCar.position.status || 'OnTrack'}</span>
+            </div>
+            <dl>
+              <Metric label="SPD" value={selectedCar.telemetry?.Speed} suffix="km/h" />
+              <Metric label="THR" value={selectedCar.telemetry?.Throttle} suffix="%" />
+              <Metric label="BRK" value={selectedCar.telemetry?.Brake} suffix="%" />
+              <Metric label="DRS" value={selectedCar.telemetry?.DRS} />
+              <Metric label="GEAR" value={selectedCar.telemetry?.NGear} />
+            </dl>
+          </div>
+        )}
+      </div>
+    </section>
+  )
+}
+
+function Metric({ label, value, suffix = '' }: { label: string; value: number | undefined; suffix?: string }) {
+  return (
+    <>
+      <dt>{label}</dt>
+      <dd>{value === undefined ? '-' : `${value}${suffix}`}</dd>
+    </>
+  )
+}
+
+function teamColor(info: LiveDriverInfo | undefined): string {
+  const raw = info?.TeamColour?.trim()
+  if (!raw) return '#777777'
+  return raw.startsWith('#') ? raw : `#${raw}`
+}