feat(po): include additional_attachments in send-email webhook

src/app/api/v1/purchase-orders/[id]/send-email/route.ts

@@ -146,6 +146,17 @@ export async function POST(
   const supplierName =
     result.purchaseOrder.expand?.supplier?.suppliername || "";
 
+  // Additional files (supplier quote, drawing, NDA) the operator
+  // wants to send with this PO. Sits alongside `documents` (the
+  // versioned PDF). The n8n workflow reads this array and attaches
+  // each token to the outbound SMTP message via the PB file proxy.
+  const additionalRaw = result.purchaseOrder.additional_attachments ?? [];
+  const additionalAttachments = Array.isArray(additionalRaw)
+    ? additionalRaw
+    : additionalRaw
+    ? [additionalRaw]
+    : [];
+
   const webhookBody = {
     trigger: "manual_send",
     poId,
@@ -186,6 +197,10 @@ export async function POST(
           },
         ]
       : [],
+    // string[] of PB-stored tokens. The n8n workflow fetches each
+    // file via the PB file proxy and attaches it to the outbound
+    // SMTP message alongside `attachments` (the versioned PO PDF).
+    additional_attachments: additionalAttachments,
     // PB admin token + URL, used by the workflow's HTTP Request node
     // to fetch the PDF directly from PB (Bearer-equivalent). PB
     // accepts the admin token in either `Authorization: <token>` or