fix: repair Mermaid diagram syntax errors and add PRD task plan

04 - Flows/Delivery Confirmation Flow.md

@@ -64,9 +64,11 @@ sequenceDiagram
     B->>FE: Enter code in dashboard
     FE->>BE: POST /api/marketplace/purchase-requests/{id}/verify-delivery {code}
     BE->>DB: match code, expires>now, !used
-    BE->>DB: deliveryCodeUsed=true; status="delivered"
+    BE->>DB: set deliveryCodeUsed = true
+    BE->>DB: set status = "delivered"
     BE->>IO: emit request-{id} 'purchase-request-update' status-changed
-    BE->>B,S: notifyDeliveryConfirmed
+    BE->>B: notifyDeliveryConfirmed
+    BE->>S: notifyDeliveryConfirmed
     Note over BE: Auto-release timer (planned) → seller_paid → payout
 ```