feat(#76): bound primary-route fetches and local-first driver summary

Add shared apiFetch timeouts/abort/typed errors with in-flight dedupe, a
RouteState UI for loading/empty/timeout/error+retry, and wire it through
Weekend (Data Health), Championship, Driver Profile, Briefing, Live, and
Race Hub. Driver summary is local-first with bounded optional OpenF1
enrichment so a hung remote call cannot block the profile.

Spike note: parseSourceMode defaults to openf1; driver summary now treats
omitted ?source= as auto so local season data is preferred.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/RouteState.tsx

@@ -0,0 +1,162 @@
+import type { ReactNode } from 'react'
+import { isTimeoutError, userFacingError } from '../lib/fetch'
+
+/** Weekend Context terminology for coverage / availability indicators. */
+export type DataAvailability = 'local' | 'partial' | 'stale' | 'archive' | 'limited' | 'missing'
+
+export function availabilityLabel(kind: DataAvailability): string {
+  switch (kind) {
+    case 'local':
+      return 'Local'
+    case 'partial':
+      return 'Partial'
+    case 'stale':
+      return 'Stale'
+    case 'archive':
+      return 'Archive'
+    case 'limited':
+      return 'Limited'
+    case 'missing':
+      return 'Missing'
+  }
+}
+
+export function AvailabilityBadge({ kind, label }: { kind: DataAvailability; label?: string }) {
+  return (
+    <span className={`badge badge-${kind === 'archive' ? 'none' : kind}`} data-testid={`availability-${kind}`}>
+      {label ?? availabilityLabel(kind)}
+    </span>
+  )
+}
+
+export type RouteStateKind = 'loading' | 'empty' | 'error' | 'timeout'
+
+interface RouteStateProps {
+  kind: RouteStateKind
+  title?: string
+  message?: ReactNode
+  error?: unknown
+  onRetry?: () => void
+  retrying?: boolean
+  testId?: string
+  className?: string
+  /** Optional availability strip (stale/limited/partial) above the state body. */
+  availability?: DataAvailability
+  children?: ReactNode
+}
+
+const DEFAULT_TITLES: Record<RouteStateKind, string> = {
+  loading: 'Loading…',
+  empty: 'Nothing here yet',
+  error: 'Could not load this view',
+  timeout: 'Request timed out',
+}
+
+const DEFAULT_MESSAGES: Record<RouteStateKind, string> = {
+  loading: 'Fetching the latest local data.',
+  empty: 'No data is available for this view yet.',
+  error: 'Something went wrong. Retry to try again.',
+  timeout: 'This request took too long. Check your connection, then retry.',
+}
+
+/**
+ * Shared primary-route state surface: loading, empty, timeout/error + retry.
+ * Retry is a real <button> (keyboard accessible) and callers should gate
+ * concurrent refetches via React Query / deduped apiFetch.
+ */
+export function RouteState({
+  kind,
+  title,
+  message,
+  error,
+  onRetry,
+  retrying = false,
+  testId,
+  className = '',
+  availability,
+  children,
+}: RouteStateProps) {
+  const resolvedKind: RouteStateKind =
+    kind === 'error' && isTimeoutError(error) ? 'timeout' : kind
+
+  const resolvedMessage =
+    message ??
+    (error != null && (resolvedKind === 'error' || resolvedKind === 'timeout')
+      ? userFacingError(error)
+      : DEFAULT_MESSAGES[resolvedKind])
+
+  const showRetry =
+    (resolvedKind === 'error' || resolvedKind === 'timeout') && typeof onRetry === 'function'
+
+  return (
+    <div
+      className={`route-state route-state-${resolvedKind} ${className}`.trim()}
+      data-testid={testId ?? `route-state-${resolvedKind}`}
+      role={resolvedKind === 'error' || resolvedKind === 'timeout' ? 'alert' : undefined}
+    >
+      {availability && (
+        <div className="route-state-availability">
+          <AvailabilityBadge kind={availability} />
+        </div>
+      )}
+      {resolvedKind === 'loading' ? (
+        <div className="loading-state">{title ?? 'loading…'}</div>
+      ) : (
+        <>
+          <div className="route-state-title">{title ?? DEFAULT_TITLES[resolvedKind]}</div>
+          <div className="route-state-message">{resolvedMessage}</div>
+          {children}
+          {showRetry && (
+            <button
+              type="button"
+              className="route-state-retry"
+              onClick={onRetry}
+              disabled={retrying}
+              aria-busy={retrying || undefined}
+            >
+              {retrying ? 'Retrying…' : 'Retry'}
+            </button>
+          )}
+        </>
+      )}
+    </div>
+  )
+}
+
+interface StaleNoticeProps {
+  availability?: DataAvailability
+  message?: string
+  onRetry?: () => void
+  testId?: string
+}
+
+/** Inline notice when a successful payload is limited/stale/partial. */
+export function DataNotice({
+  availability = 'stale',
+  message,
+  onRetry,
+  testId = 'data-notice',
+}: StaleNoticeProps) {
+  const defaultMessage =
+    availability === 'stale'
+      ? 'Showing stale cached data. Retry to refresh.'
+      : availability === 'limited'
+        ? 'Some optional details are unavailable. Core local data is shown.'
+        : availability === 'partial'
+          ? 'Coverage is partial for this weekend.'
+          : availability === 'archive'
+            ? 'Showing an archived snapshot.'
+            : 'Data availability is limited.'
+
+  return (
+    <div className="data-notice" data-testid={testId} role="status">
+      <AvailabilityBadge kind={availability} />
+      <span className="data-notice-text">{message ?? defaultMessage}</span>
+      {onRetry && (
+        <button type="button" className="route-state-retry data-notice-retry" onClick={onRetry}>
+          Retry
+        </button>
+      )}
+    </div>
+  )
+}