feat(ST-1109.8): show PBI status badge and consolidate filters into popover

- Pbi.status (lowercase API) flows from page.tsx via pbiStatusToApi
- Status badge rendered in BacklogCard's badge slot using PBI_STATUS_COLORS
- Two old Select dropdowns replaced by single Popover with three pill-button
  sections (Sorteren, Prioriteit, Status) and a "Wis filters" footer
- Filter trigger shows active count "(n)" badge in label
- Active priority/status filters still surface as dismissable chips next to
  the trigger for at-a-glance feedback
- onEdit passes the full Pbi (incl. status) so the dialog opens with the
  correct current status — closes the data flow loop opened in ST-1109.7

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

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

@@ -2,6 +2,7 @@ import { notFound, redirect } from 'next/navigation'
 import { getSession } from '@/lib/auth'
 import { getAccessibleProduct } from '@/lib/product-access'
 import { prisma } from '@/lib/prisma'
+import { pbiStatusToApi } from '@/lib/task-status'
 import { SplitPane } from '@/components/split-pane/split-pane'
 import { PbiList } from '@/components/backlog/pbi-list'
 import { StoryPanel } from '@/components/backlog/story-panel'
@@ -94,7 +95,7 @@ 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, created_at: p.created_at }))}
+              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, status: pbiStatusToApi(p.status) }))}
               isDemo={isDemo}
             />
           }