feat(PBI-74): oude stores opruimen (Story 8)

Workspace-store is nu de enige bron voor product-backlog client-state. De
vier voorgangers en de dual-dispatch-infrastructuur zijn verwijderd.

- T-872: grep over codebase op useBacklogStore/usePlannerStore/
  useSelectionStore/useProductStore is leeg.
- T-873..T-876: stores/{backlog,planner,selection,product}-store.ts deleted.
- T-877: __tests__/realtime/payload-contract.test.ts en
  __tests__/api/backlog-realtime.test.ts deleted — pbi/story/task I|U|D
  payload-handling wordt al gedekt door
  __tests__/stores/product-workspace/store.test.ts (incl. parent-move,
  idempotent inserts, delete-cleanup).
- T-878: lib/realtime/dev-workspace-fingerprint.ts deleted, dual-dispatch
  uit BacklogHydrationWrapper en lib/realtime/use-backlog-realtime.ts
  weggehaald. stores/products-store.ts (lijst van producten ≠ active
  product) blijft ongewijzigd.

Bijwerkingen:
- BacklogPbi en BacklogStory types in components/backlog/story-panel.tsx en
  components/sprint/sprint-backlog.tsx krijgen sort_order zodat ze met de
  workspace-types overeenkomen.
- Server-pages /products/[id]/page.tsx (desktop+mobile) en
  /products/[id]/sprint/[sprintId]/page.tsx selecteren sort_order op story
  en mappen het door in de hydration-payload.

Verify: lint+typecheck clean, 626/626 tests groen (verlies van 25 redundante
oude-store tests; workspace-store tests dekken hetzelfde gedrag).

Refs: PBI-74, ST-1325, T-872..T-878

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/realtime/dev-workspace-fingerprint.ts

@@ -1,71 +0,0 @@
-// PBI-74 / T-846: dev-only schaduw-store fingerprint verifyer.
-// Logt counts van oude (useBacklogStore) en nieuwe (useProductWorkspaceStore)
-// na elke hydratie- of realtime-event. Bij mismatch verschijnt er een
-// console.warn zodat we tijdens Story 2 in dev-tools zien dat beide stores
-// dezelfde inhoud houden.
-//
-// TODO(PBI-74 / Story 8 / T-878): verwijder dit bestand en alle aanroepen
-// vóór merge van de cleanup-PR.
-
-import { useBacklogStore } from '@/stores/backlog-store'
-import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
-
-interface Fingerprint {
-  pbis: number
-  storiesByPbi: Record<string, number>
-  tasksByStory: Record<string, number>
-}
-
-function fingerprintOld(): Fingerprint {
-  const s = useBacklogStore.getState()
-  const storiesByPbi: Record<string, number> = {}
-  for (const [pbiId, list] of Object.entries(s.storiesByPbi)) {
-    storiesByPbi[pbiId] = list.length
-  }
-  const tasksByStory: Record<string, number> = {}
-  for (const [storyId, list] of Object.entries(s.tasksByStory)) {
-    tasksByStory[storyId] = list.length
-  }
-  return { pbis: s.pbis.length, storiesByPbi, tasksByStory }
-}
-
-function fingerprintNew(): Fingerprint {
-  const s = useProductWorkspaceStore.getState()
-  const storiesByPbi: Record<string, number> = {}
-  for (const [pbiId, ids] of Object.entries(s.relations.storyIdsByPbi)) {
-    storiesByPbi[pbiId] = ids.length
-  }
-  const tasksByStory: Record<string, number> = {}
-  for (const [storyId, ids] of Object.entries(s.relations.taskIdsByStory)) {
-    tasksByStory[storyId] = ids.length
-  }
-  return { pbis: s.relations.pbiIds.length, storiesByPbi, tasksByStory }
-}
-
-function shapeEqual(a: Record<string, number>, b: Record<string, number>): boolean {
-  const keys = new Set([...Object.keys(a), ...Object.keys(b)])
-  for (const k of keys) {
-    if ((a[k] ?? 0) !== (b[k] ?? 0)) return false
-  }
-  return true
-}
-
-export function logWorkspaceFingerprint(label: string): void {
-  if (process.env.NODE_ENV === 'production') return
-
-  const oldFp = fingerprintOld()
-  const newFp = fingerprintNew()
-  const match =
-    oldFp.pbis === newFp.pbis &&
-    shapeEqual(oldFp.storiesByPbi, newFp.storiesByPbi) &&
-    shapeEqual(oldFp.tasksByStory, newFp.tasksByStory)
-
-  if (!match) {
-    console.warn(
-      `[workspace-fingerprint:${label}] MISMATCH oud↔nieuw`,
-      { old: oldFp, new: newFp },
-    )
-  } else if (process.env.NEXT_PUBLIC_DEBUG_WORKSPACE_FINGERPRINT === '1') {
-    console.debug(`[workspace-fingerprint:${label}] match`, oldFp)
-  }
-}

lib/realtime/use-backlog-realtime.ts

@@ -1,24 +1,19 @@
 'use client'
 
-// ST-1115: Client hook for the backlog 3-pane SSE stream.
+// ST-1115 / PBI-74: Client hook for the backlog 3-pane SSE stream.
 // Mounts in BacklogHydrationWrapper so it survives Server Action refreshes.
-// Dispatches pbi/story/task change events into useBacklogStore.applyChange.
+// Dispatches pbi/story/task change events into useProductWorkspaceStore.
 //
-// PBI-74 / T-845: dual-dispatch — events worden ook naar de nieuwe
-// product-workspace-store gestuurd. De oude store blijft leidend totdat
-// Story 3 de UI-consumers heeft omgezet en Story 8 de oude store opruimt.
-// PBI-74 / T-861: stream blijft open op tab hidden. Per spec werkt
-// EventSource gewoon door als de browser het toelaat — gemiste events
-// worden opgehaald via resyncActiveScopes('visible') uit useWorkspaceResync.
-// PBI-74 / T-862: bij latere 'ready' events (post-reconnect) triggeren we
+// T-861: stream blijft open op tab hidden. Per spec werkt EventSource gewoon
+// door als de browser het toelaat — gemiste events worden opgehaald via
+// resyncActiveScopes('visible') uit useWorkspaceResync.
+// T-862: bij latere 'ready' events (post-reconnect) triggeren we
 // resyncActiveScopes('reconnect') zodat events die tijdens disconnect zijn
 // gemist, alsnog binnenkomen.
 
 import { useEffect, useRef } from 'react'
-import { useBacklogStore } from '@/stores/backlog-store'
 import { useProductWorkspaceStore } from '@/stores/product-workspace/store'
 import type { ProductRealtimeEvent } from '@/stores/product-workspace/types'
-import { logWorkspaceFingerprint } from '@/lib/realtime/dev-workspace-fingerprint'
 
 const BACKOFF_START_MS = 1_000
 const BACKOFF_MAX_MS = 30_000
@@ -71,15 +66,9 @@ export function useBacklogRealtime(productId: string | null) {
         if (!e.data) return
         try {
           const payload = JSON.parse(e.data) as EntityPayload
-          // Oude store (leidend voor UI tot Story 3).
-          useBacklogStore
-            .getState()
-            .applyChange(payload.entity, payload.op, payload as Record<string, unknown>)
-          // Nieuwe workspace-store (schaduw — wordt leidend in Story 3).
           useProductWorkspaceStore
             .getState()
             .applyRealtimeEvent(payload as unknown as ProductRealtimeEvent)
-          logWorkspaceFingerprint(`event:${payload.entity}:${payload.op}`)
         } catch (err) {
           if (process.env.NODE_ENV !== 'production') {
             console.error('[realtime/backlog] failed to parse event', err, e.data)