feat(M9): active product backlog — persistent active PB, NavBar splits, sprint card styling (#10)

* feat(tooling): extend backlog parser to support PBI-x milestone headers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore(backlog): mark ST-801–806 as done

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(backlog): sorteer PBI's en stories op prio/code/datum, onthoud keuze in localStorage; vergroot sprint-afronden dialoog

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(ST-901): add user.active_product_id with FK to Product

- Nullable relation User → Product with onDelete: SetNull
- Index on active_product_id for join performance
- Migration: 20260427165329_add_user_active_product_id
- Install @tanstack/react-table (was missing from node_modules)
- Fix PRIORITY_COLORS ref removed in earlier refactor
- Note: User schema change affects vendor/scrum4me-mcp submodule — run prisma generate + tsc --noEmit there after merge

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: restore priority color on PBI filter pill

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(ST-902): add setActiveProduct + clearActiveProduct server actions

- actions/active-product.ts: setActiveProductAction validates access via
  productAccessFilter, rejects archived products and demo users
- archiveProductAction: clears active_product_id for all affected users in transaction
- removeProductMemberAction: clears active_product_id for removed member
- leaveProductAction: clears active_product_id for leaving user

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(ST-903): load active product in layout, replace cookie with DB lookup in solo

- layout.tsx: fetch active_product_id, resolve product, clear stale ref server-side
- NavBar: add activeProduct prop (rendering changes in ST-904)
- solo/page.tsx: redirect via user.active_product_id instead of lastProductId cookie
- proxy.ts: remove lastProductId cookie logic
- lib/cookies.ts: deleted (no longer used)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(ST-904): split NavBar into 5 tabs with disabled-states and product-switcher dropdown

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* feat(ST-905): add Activeer button per product row in dashboard and product header

* feat(ST-906): redirect to dashboard with toast when active product becomes inaccessible

* feat(ST-907): tests for active-product actions and functional spec update for M9

* docs(M9): add implementation plan document and link from backlog

* feat: active PB indicator, Maak actief button and new product link in settings

* feat: apply priority-color card style to sprint story rows

* fix: move add-to-sprint click from entire card to + Toevoegen button

* feat: apply priority-color card style to sprint task rows

* fix(sprint-backlog): prevent text selection on PBI collapse button

* chore: bump version to 0.4.0 (M9 active product backlog)

* fix(landing): align logged-in nav left to match app NavBar

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

app/(app)/products/[id]/page.tsx

@@ -7,6 +7,7 @@ import { PbiList } from '@/components/backlog/pbi-list'
 import { StoryPanel } from '@/components/backlog/story-panel'
 import type { Story } from '@/components/backlog/story-panel'
 import { StartSprintButton } from '@/components/sprint/start-sprint-button'
+import { ActivateProductButton } from '@/components/shared/activate-product-button'
 import Link from 'next/link'
 
 interface Props {
@@ -21,9 +22,10 @@ export default async function ProductBacklogPage({ params }: Props) {
   const product = await getAccessibleProduct(id, session.userId)
   if (!product) notFound()
 
-  const activeSprint = await prisma.sprint.findFirst({
-    where: { product_id: id, status: 'ACTIVE' },
-  })
+  const [activeSprint, user] = await Promise.all([
+    prisma.sprint.findFirst({ where: { product_id: id, status: 'ACTIVE' } }),
+    prisma.user.findUnique({ where: { id: session.userId! }, select: { active_product_id: true } }),
+  ])
 
   const pbis = await prisma.pbi.findMany({
     where: { product_id: id },
@@ -42,6 +44,7 @@ export default async function ProductBacklogPage({ params }: Props) {
       priority: true,
       status: true,
       pbi_id: true,
+      created_at: true,
     },
   })
 
@@ -65,6 +68,9 @@ export default async function ProductBacklogPage({ params }: Props) {
           )}
         </div>
         <div className="flex items-center gap-3">
+          {user?.active_product_id !== id && (
+            <ActivateProductButton productId={id} isDemo={isDemo} redirectTo={`/products/${id}`} />
+          )}
           {activeSprint ? (
             <Link href={`/products/${id}/sprint`} className="text-xs text-primary hover:underline font-medium">
               Sprint actief →
@@ -88,7 +94,7 @@ export default async function ProductBacklogPage({ params }: Props) {
           left={
             <PbiList
               productId={id}
-              pbis={pbis.map((p: (typeof pbis)[number]) => ({ id: p.id, code: p.code, title: p.title, priority: p.priority, description: p.description }))}
+              pbis={pbis.map((p: (typeof pbis)[number]) => ({ id: p.id, code: p.code, title: p.title, priority: p.priority, description: p.description, created_at: p.created_at }))}
               isDemo={isDemo}
             />
           }