fix(W2): graceful skip when customer link not yet filled (no crash)

When CP record is drafted with product set before customer,
the webhook fires with customerId=null -> now returns
skipWriteBack=true (routed to No-op) instead of throwing.
Record re-fires webhook properly once customer field is set.

n8n/w2-compute.js

@@ -38,7 +38,11 @@ const custProdId = $json.customerProductId;
 // 1. re-fetch the CP record
 const cp = await ncGet(`/api/v2/tables/${T_CUSTPROD}/records/${custProdId}`);
 const customerId = linkId(cp.customer);
-if (!customerId) throw new Error('CP has no customer link');
+if (!customerId) {
+  // Gracefully skip when customer link not yet filled (CP record is being drafted).
+  // The webhook will re-fire when customer is set later.
+  return { json: { skipWriteBack: true, customerProductId: custProdId, reason: 'no customer link yet' } };
+}
 
 // 2. load all active CPs for this customer
 const cps = await ncGet(`/api/v2/tables/${T_CUSTPROD}/records?where=(customer,eq,${customerId})&limit=1000`);