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>

app/_components/tasks/status-select.tsx

@@ -15,10 +15,11 @@ const STATUS_CONFIG: Record<TaskStatus, { label: string; dot: string }> = {
   REVIEW: { label: 'Review', dot: 'bg-status-review' },
   DONE: { label: 'Klaar', dot: 'bg-status-done' },
   FAILED: { label: 'Gefaald', dot: 'bg-status-failed' },
+  EXCLUDED: { label: 'Uitgesloten', dot: 'bg-muted-foreground/40' },
 }
 
 // FAILED ontbreekt bewust: alleen via sprint-cascade gezet, niet handmatig kiesbaar.
-const STATUS_ORDER: TaskStatus[] = ['TO_DO', 'IN_PROGRESS', 'REVIEW', 'DONE']
+const STATUS_ORDER: TaskStatus[] = ['TO_DO', 'IN_PROGRESS', 'REVIEW', 'DONE', 'EXCLUDED']
 
 function StatusIndicator({ status }: { status: TaskStatus }) {
   return (