fix(#73): consume canonical Weekend Context contract and repair navigation

Address the independent review blockers on PR #80 after rebasing onto the
authoritative #72 Weekend Context API.

- Replace the invented frontend WeekendContext with the exact backend contract
  (temporal_state, previous/focus/next meetings, previous_completed/active/next/
  default_analysis sessions with availability). Every valid canonical payload now
  maps to a designed state via a total resolveViewState; a well-formed response
  can never fall through to the limited-data placeholder.
- Make the canonical read the single source of truth: useWeekendContext no longer
  fans out to season/meetings/per-weekend/OpenF1/live queries. Only supplementary
  championship + news reads run, and only once the canonical context resolves.
- Fix the Prepare/analysis flow: /preview is a stable alias that renders the
  preparation surface (PreSessionView) instead of redirecting back to the same
  between-races screen.
- One primary navigation system per breakpoint: the mobile top-bar links are
  hidden so the bottom bar is the sole primary nav, and Admin is moved out of
  every Primary landmark into an operator-utilities toolbar.
- Add Vitest coverage for the contract mapping, every temporal state, loading/
  error/limited surfaces, the no-fanout guarantee, the /preview CTA, and the nav
  hierarchy; add hermetic Playwright journeys (seeded + injected canonical
  payloads), 390/768/1440 overflow checks, and Weekend visual snapshots. Retire
  the stale Command Center specs/snapshots.

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

frontend/src/types.ts

@@ -449,67 +449,73 @@ export interface DriverSummary {
 }
 
 // ── Weekend Context ──
-// Canonical contract for the adaptive Weekend home. Served by
-// /api/v1/weekend-context (sibling backend story #72) and, until that endpoint
-// ships, derived client-side from existing endpoints (see lib/weekendContext.ts).
-export type WeekendState =
-  | 'loading'
-  | 'error'
-  | 'limited_data'
-  | 'between_races'
+// Canonical local-first contract for the adaptive Weekend home, served verbatim
+// by /api/v1/weekend-context (backend story #72, internal/query/context.go).
+// The frontend consumes this shape as the single source of truth; view-model
+// derivation lives in lib/weekendContext.ts.
+
+// TemporalState mirrors query.TemporalState exactly (the JSON `temporal_state`).
+export type TemporalState =
+  | 'no_season'
+  | 'between_weekends'
   | 'pre_session'
-  | 'between_sessions'
   | 'session_live'
   | 'session_settling'
+  | 'between_sessions'
   | 'post_weekend'
   | 'season_complete'
 
-export interface WeekendPodiumEntry {
-  position: number
-  driver_number: number
-  name_acronym: string
-  team_name: string
-  team_colour: string
-  gap: string
+// ContextAvailability mirrors query.ContextAvailability. Every field is present
+// in a canonical payload except the optional `observed_at`.
+export interface ContextAvailability {
+  schedule: string
+  live_transport: string
+  live_session: string
+  archive: string
+  local_analysis: string
+  freshness: string
+  observed_at?: string
+  limitations: string[]
 }
 
-export type WeekendSessionStatus = 'done' | 'live' | 'next' | 'upcoming'
-
-export interface WeekendTimelineSession {
-  session_key: number
-  session_name: string
-  session_type: string
-  date_start: string
-  date_end: string
-  status: WeekendSessionStatus
+// ContextSession mirrors query.ContextSession: a session identity coupled with
+// its meeting and structured availability contract.
+export interface ContextSession {
+  session: Session
+  meeting?: Meeting
+  availability: ContextAvailability
 }
 
-export interface WeekendCompletedEvent {
-  meeting_key: number
-  meeting_name: string
-  country_code: string
-  country_flag: string
-  circuit_short_name: string
-  round?: number
-  analysis_session_key: number
-  analysis_session_name: string
-  label: string
-  podium: WeekendPodiumEntry[]
-  story?: string
+// WeekendContext mirrors query.WeekendContext (the canonical endpoint body).
+export interface WeekendContext {
+  season?: number
+  temporal_state: TemporalState
+  previous_meeting?: Meeting
+  focus_meeting?: Meeting
+  next_meeting?: Meeting
+  previous_completed_session?: ContextSession
+  active_session?: ContextSession
+  next_session?: ContextSession
+  default_analysis_session?: ContextSession
+  championship_round: number
+  total_championship_rounds: number
 }
 
-export interface WeekendUpcomingEvent {
-  meeting_key: number
-  meeting_name: string
-  country_code: string
-  country_flag: string
-  circuit_short_name: string
-  circuit_key?: number
-  round?: number
-  date_start?: string
-  next_session_name?: string
-  next_session_start?: string
-}
+// ── Weekend view model (client-only) ──
+// The rendered Weekend home layers a small set of non-canonical UI states
+// (loading/error) plus supplementary data (championship movers, briefing) on top
+// of the canonical context. None of these are part of the #72 contract.
+export type WeekendViewState =
+  | 'loading'
+  | 'error'
+  | 'no_season'
+  | 'between_weekends'
+  | 'pre_session'
+  | 'session_live'
+  | 'session_settling'
+  | 'between_sessions'
+  | 'post_weekend'
+  | 'season_complete'
 
 export interface WeekendChampionshipMover {
   position: number
@@ -534,32 +540,13 @@ export interface WeekendBriefingItem {
   image_url?: string
 }
 
-export type WeekendRoundStatus = 'completed' | 'next' | 'upcoming'
-
-export interface WeekendSeasonRound {
-  round: number
-  meeting_key: number
-  country_code: string
-  country_flag: string
-  status: WeekendRoundStatus
-  analysis_session_key?: number
-}
-
-export interface WeekendContext {
-  state: WeekendState
-  season: number
-  message?: string
-  live?: boolean
-  active_meeting_name?: string
-  active_circuit_short_name?: string
-  last_event?: WeekendCompletedEvent
-  next_event?: WeekendUpcomingEvent
-  last_session?: WeekendCompletedEvent
-  next_session?: WeekendTimelineSession
-  sessions?: WeekendTimelineSession[]
-  championship_impact?: WeekendChampionshipImpact
-  season_rounds?: WeekendSeasonRound[]
-  briefing?: WeekendBriefingItem[]
+export interface WeekendPodiumEntry {
+  position: number
+  driver_number: number
+  name_acronym: string
+  team_name: string
+  team_colour: string
+  gap: string
 }
 
 export interface NewsItem {