feat(peppol): poll outbound delivery status + cap receiving registrations (#1793)

* feat(peppol): poll outbound delivery status from the access point

Qvalia's webhook API answers 404 on its production host (the sandbox answers
204), so without this the prod lifecycle would stop at submission_accepted.
The transport gains pollDeliveryStatus(); the Qvalia adapter reads
/invoices/outgoing/status and maps the message-log status through the same
tolerant mapping as a document_delivery webhook, with the same dedupe key, so
a later webhook for the same transition is a harmless duplicate. A cron four
times an hour walks the open deliveries of the last 45 days, records the
answer through the append-only lifecycle RPC and fetches evidence once a
delivery reaches transport or a terminal state. Kept as the safety net for a
missed webhook once Qvalia ships them to prod.

Refs #546

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TqFpxeWqbpR7bcwUJLRERQ

* feat(peppol): cap receiving registrations at the contracted tenant count

The Qvalia partner contract is priced per tenant (10 to start), so the
registration refuses the next company with PEPPOL_REGISTRATION_CAP_REACHED
once PEPPOL_RECEIVING_MAX_REGISTRATIONS live registrations exist, instead of
silently exceeding the contract. A company that already holds a live row is
never counted twice; unset means no cap (own provider account).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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>

lib/errors/structured-errors.ts

@@ -1330,6 +1330,11 @@ const INVOICE: Record<string, StructuredErrorEntry> = {
     message_sv: 'Bolaget är inte registrerat för Peppol-mottagning.',
     message_en: 'The company is not registered for Peppol receiving.',
   },
+  PEPPOL_REGISTRATION_CAP_REACHED: {
+    httpStatus: 409,
+    message_sv: 'Alla platser för Peppol-mottagning är upptagna just nu. Hör av dig till support så öppnar vi fler. Att skicka e-fakturor fungerar ändå.',
+    message_en: 'All Peppol receiving slots are taken right now. Contact support and we will open more. Sending e-invoices works regardless.',
+  },
 }
 
 const SUPPLIER_INVOICE: Record<string, StructuredErrorEntry> = {