fix(peppol): read Qvalia's prefixed UBL-JSON keys, add incoming probe (#1786)

Qvalia's UBL-JSON keeps namespace prefixes (cac:AccountingSupplierParty,
cbc:EndpointID) with attributes under `$` (verified live 2026-08-21 on the
inbound test invoice Joanna sent to 0007:5595386219), not the unprefixed
OASIS form the 409-recovery extractor assumed. Accept both. The probe gains
`incoming [integrationId]` to list inbound statuses or print one inbound
invoice as XML without marking it read.

Refs #546


Claude-Session: https://claude.ai/code/session_01TqFpxeWqbpR7bcwUJLRERQ

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

scripts/peppol/qvalia-probe.ts

@@ -16,6 +16,9 @@
  *       Lists the Peppol identifiers registered on the partner account.
  *   npx tsx scripts/peppol/qvalia-probe.ts outgoing
  *       Lists the three latest outgoing invoice statuses (read-only).
+ *   npx tsx scripts/peppol/qvalia-probe.ts incoming [integrationId]
+ *       Lists the latest incoming invoice statuses, or prints one incoming
+ *       invoice as XML (read-only: uses the non-marking endpoint).
  *   npx tsx scripts/peppol/qvalia-probe.ts send path/to/invoice.xml
  *       Submits a BIS Billing 3 XML through the adapter. Sandbox only: the
  *       script refuses a production base URL.
@@ -110,6 +113,22 @@ async function main(): Promise<void> {
       )
       return
     }
+    case 'incoming': {
+      if (argument) {
+        const response = await fetch(
+          `${config!.baseUrl}/partner/${partner}/transaction/${account}/invoices/incoming?integrationId=${encodeURIComponent(argument)}&includeRead=true&limit=1`,
+          { headers: { Authorization: headerFor(config!.authScheme), accept: 'application/xml' } },
+        )
+        console.log(`HTTP ${response.status}`)
+        console.log((await response.text()).slice(0, 6000))
+        return
+      }
+      await show(
+        'GET /partner/{p}/transaction/{a}/invoices/incoming/status',
+        await rawGet(`/partner/${partner}/transaction/${account}/invoices/incoming/status?includeRead=true&limit=5`),
+      )
+      return
+    }
     case 'webhook': {
       await show('GET /partner/{p}/webhook/configure', await rawGet(`/partner/${partner}/webhook/configure`))
       return