feat(race-hub): trustworthy defaults and fan-facing analysis hierarchy (#75)

Make bare /race-hub resolve to a completed session and never open empty
post-session analysis for a future race.

- Backend: add `default_analysis_session` to the Weekend context. It never
  resolves to a future session (picks the richest completed session, ties
  toward the later one; 0 when everything is upcoming). Existing
  `default_session_key` and deep links are unchanged.
- Frontend default resolution prefers the most recently completed weekend
  (`pickAnalysisFocusMeeting`) and consumes `default_analysis_session`, falling
  back to the switcher when only upcoming sessions exist.
- New `sessionState` lib maps timing + coverage to user language
  (upcoming/live/preparing/partial/ready/cancelled); the session rail, active
  sub-bar, and WeekendSwitcher now label states instead of raw x/11 counts.
- Future sessions render a purpose-built PreSessionView (expected availability +
  countdown) instead of empty Winner/Podium/Pole/Strategy/Compare cards.
- Analysis navigation regrouped into Story / Analysis / Data & Context; every
  existing tab is preserved. Diagnostics (renamed from Data Status) is now a
  secondary action and the raw dataset strip is hidden behind an explicit
  toggle, so operational coverage no longer precedes fan content.
- Loading/error states offer Retry and a path back to Weekend.

Tests: Go query tests for future-exclusion; Vitest for default selection,
future pre-session, partial state, error/retry, grouped nav, and sessionState;
hermetic Playwright for bare/completed/future/return-to-Weekend; new
race-hub-future visual snapshots. Seed adds a far-future session inside the
Monaco meeting (kept in-meeting so Command Center focus is unaffected).

Note: `default_analysis_session` is an additive field on the existing
`/weekend` contract (no new endpoint), per the spec's "context contract" scope.

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

frontend/src/lib/sessionState.ts

@@ -0,0 +1,100 @@
+import type { WeekendSession } from '../types'
+import { isSessionComplete } from './coverage'
+import { sessionEndTime, sessionStartTime } from './schedule'
+
+/**
+ * User-facing lifecycle state for a weekend session. Combines the schedule
+ * (has it started / finished) with local dataset coverage so the UI can speak
+ * in fan language instead of raw `x/11` coverage counts.
+ *
+ * - `upcoming`   — starts in the future; render a pre-session view.
+ * - `live`       — currently running (started, not yet finished).
+ * - `preparing`  — finished (or unknown timing) but no local analysis yet.
+ * - `partial`    — finished with some, but not all, local datasets.
+ * - `ready`      — finished with full local coverage; analysis is trustworthy.
+ * - `cancelled`  — session was cancelled.
+ */
+export type SessionState =
+  | 'upcoming'
+  | 'live'
+  | 'preparing'
+  | 'partial'
+  | 'ready'
+  | 'cancelled'
+
+export function sessionState(session: WeekendSession, now: Date): SessionState {
+  if (session.source === 'cancelled') return 'cancelled'
+
+  const start = sessionStartTime(session.session)
+  const end = sessionEndTime(session.session)
+
+  if (start && start > now) return 'upcoming'
+  if (start && end && now >= start && now < end) return 'live'
+
+  // Session has started/finished (or timing unknown) — describe it by coverage.
+  if (isSessionComplete(session.datasets)) return 'ready'
+  if (session.source === 'none') return 'preparing'
+  return 'partial'
+}
+
+/** Short label suitable for chips and the session switcher. */
+export function sessionStateLabel(state: SessionState): string {
+  switch (state) {
+    case 'upcoming':
+      return 'Upcoming'
+    case 'live':
+      return 'Live'
+    case 'preparing':
+      return 'Preparing'
+    case 'partial':
+      return 'Partial'
+    case 'ready':
+      return 'Ready'
+    case 'cancelled':
+      return 'Cancelled'
+  }
+}
+
+/** Longer, sentence-style description for headers and empty states. */
+export function sessionStateDescription(state: SessionState): string {
+  switch (state) {
+    case 'upcoming':
+      return 'Session has not started yet.'
+    case 'live':
+      return 'Session is running now.'
+    case 'preparing':
+      return 'Analysis is being prepared — no local data ingested yet.'
+    case 'partial':
+      return 'Partial analysis available — some datasets are still missing.'
+    case 'ready':
+      return 'Full analysis is ready.'
+    case 'cancelled':
+      return 'This session was cancelled.'
+  }
+}
+
+/**
+ * Class suffix used for the coverage dot, so the rail can colour a session by
+ * its lifecycle state rather than only by data source.
+ */
+export function sessionStateDotClass(state: SessionState): string {
+  switch (state) {
+    case 'ready':
+      return 'rh-state-ready'
+    case 'partial':
+      return 'rh-state-partial'
+    case 'live':
+      return 'rh-state-live'
+    case 'upcoming':
+      return 'rh-state-upcoming'
+    case 'cancelled':
+      return 'rh-state-cancelled'
+    default:
+      return 'rh-state-preparing'
+  }
+}
+
+/** Whether a session should render the pre-session (expected availability) view. */
+export function isPreSession(state: SessionState): boolean {
+  return state === 'upcoming'
+}