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>

prisma/migrations/20260427165329_add_user_active_product_id/migration.sql

@@ -0,0 +1,8 @@
+-- AlterTable
+ALTER TABLE "users" ADD COLUMN     "active_product_id" TEXT;
+
+-- CreateIndex
+CREATE INDEX "users_active_product_id_idx" ON "users"("active_product_id");
+
+-- AddForeignKey
+ALTER TABLE "users" ADD CONSTRAINT "users_active_product_id_fkey" FOREIGN KEY ("active_product_id") REFERENCES "products"("id") ON DELETE SET NULL ON UPDATE CASCADE;