fix: rename total to count in AIBridgeListInterceptionsResponse (#20410)

Thanks to the great work in #20393, we’ve successfully introduced
offset-based pagination for this endpoint. However, the frontend expects
a `count` field in the response rather than `total`. This PR updates the
response payload to rename the returned key to `count` for consistency
with frontend expectations and existing API patterns.

This is necessary to unblock the work in #20331

codersdk/aibridge.go

@@ -56,7 +56,7 @@ type AIBridgeToolUsage struct {
 }
 
 type AIBridgeListInterceptionsResponse struct {
-	Total   int64                  `json:"total"`
+	Count   int64                  `json:"count"`
 	Results []AIBridgeInterception `json:"results"`
 }