feat(PBI-63): meerdere sprints per product + EXCLUDED + sprint-switcher (#161)

- Sprint lifecycle: ACTIVE→OPEN, COMPLETED→CLOSED, +ARCHIVED (FAILED behouden)
- TaskStatus: +EXCLUDED (overgeslagen door agent-loop via bestaande TO_DO filter)
- Cookie-gebaseerde actieve sprint per product (lib/active-sprint.ts)
- Route splitsen: /products/[id]/sprint/[sprintId] + /sprint redirect-page
- NavBar: gestapelde product/sprint dropdowns + BUILDING-badge derivatie
- Backlog selectie-modus + nieuwe-sprint-dialog (createSprintWithPbisAction)
- Migratie 20260507210000_sprint_lifecycle: ALTER TYPE RENAME (geen data-rewrite)
- Version bump 1.0.0 → 1.2.0

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

actions/active-sprint.ts

@@ -0,0 +1,42 @@
+'use server'
+
+import { revalidatePath } from 'next/cache'
+import { cookies } from 'next/headers'
+import { getIronSession } from 'iron-session'
+import { z } from 'zod'
+import { prisma } from '@/lib/prisma'
+import { SessionData, sessionOptions } from '@/lib/session'
+import { productAccessFilter } from '@/lib/product-access'
+import { setActiveSprintCookie } from '@/lib/active-sprint'
+
+async function getSession() {
+  return getIronSession<SessionData>(await cookies(), sessionOptions)
+}
+
+const setSchema = z.object({
+  productId: z.string().min(1),
+  sprintId: z.string().min(1),
+})
+
+export async function setActiveSprintAction(productId: string, sprintId: string) {
+  const session = await getSession()
+  if (!session.userId) return { error: 'Niet ingelogd' }
+  if (session.isDemo) return { error: 'Niet beschikbaar in demo-modus' }
+
+  const parsed = setSchema.safeParse({ productId, sprintId })
+  if (!parsed.success) return { error: 'Ongeldig product- of sprint-id' }
+
+  const sprint = await prisma.sprint.findFirst({
+    where: {
+      id: parsed.data.sprintId,
+      product_id: parsed.data.productId,
+      product: productAccessFilter(session.userId),
+    },
+    select: { id: true },
+  })
+  if (!sprint) return { error: 'Sprint niet gevonden of niet toegankelijk' }
+
+  await setActiveSprintCookie(parsed.data.productId, parsed.data.sprintId)
+  revalidatePath('/', 'layout')
+  return { success: true, sprintId: parsed.data.sprintId }
+}