feat: Control-Detail Provenance + Atomare Controls Seite

Backend: provenance endpoint (obligations, doc refs, merged duplicates,
regulations summary) + atomic-stats aggregation endpoint.
Frontend: ControlDetail mit Provenance-Sektionen, klickbare Navigation,
neue /sdk/atomic-controls Seite mit Stats-Bar und gefilterer Liste.

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

admin-compliance/app/api/sdk/v1/canonical/route.ts

@@ -108,6 +108,19 @@ export async function GET(request: NextRequest) {
         break
       }
 
+      case 'provenance': {
+        const provId = searchParams.get('id')
+        if (!provId) {
+          return NextResponse.json({ error: 'Missing control id' }, { status: 400 })
+        }
+        backendPath = `/api/compliance/v1/canonical/controls/${encodeURIComponent(provId)}/provenance`
+        break
+      }
+
+      case 'atomic-stats':
+        backendPath = '/api/compliance/v1/canonical/controls/atomic-stats'
+        break
+
       case 'similar': {
         const simControlId = searchParams.get('id')
         if (!simControlId) {