Add POI feature and imporve the overall backend implementation

shared/messaging/events.py

@@ -102,3 +102,40 @@ class DataImportedEvent(BaseEvent):
             event_type="data.imported",
             correlation_id=correlation_id
         )
+
+# Procurement Events
+class PurchaseOrderApprovedEvent(BaseEvent):
+    def __init__(self, service_name: str, data: Dict[str, Any], correlation_id: Optional[str] = None):
+        super().__init__(
+            service_name=service_name,
+            data=data,
+            event_type="po.approved",
+            correlation_id=correlation_id
+        )
+
+class PurchaseOrderRejectedEvent(BaseEvent):
+    def __init__(self, service_name: str, data: Dict[str, Any], correlation_id: Optional[str] = None):
+        super().__init__(
+            service_name=service_name,
+            data=data,
+            event_type="po.rejected",
+            correlation_id=correlation_id
+        )
+
+class PurchaseOrderSentToSupplierEvent(BaseEvent):
+    def __init__(self, service_name: str, data: Dict[str, Any], correlation_id: Optional[str] = None):
+        super().__init__(
+            service_name=service_name,
+            data=data,
+            event_type="po.sent_to_supplier",
+            correlation_id=correlation_id
+        )
+
+class DeliveryReceivedEvent(BaseEvent):
+    def __init__(self, service_name: str, data: Dict[str, Any], correlation_id: Optional[str] = None):
+        super().__init__(
+            service_name=service_name,
+            data=data,
+            event_type="delivery.received",
+            correlation_id=correlation_id
+        )