update customer

internal/ucp/customer_test.go

@@ -446,13 +446,13 @@ func TestCustomerHandlerInvalidID(t *testing.T) {
 	applier := newTestProfileApplier()
 	handler := CustomerHandler(applier)
 
-	// Path "/" doesn't match the /{id} pattern — falls through to 404.
+	// Path "/" now has POST / registered (create customer), so GET / is 405.
 	// Paths with invalid base62 characters should get 400.
 	tests := []struct {
 		path           string
 		expectedStatus int
 	}{
-		{"/", http.StatusNotFound},           // doesn't match /{id}
+		{"/", http.StatusMethodNotAllowed},   // POST / exists, GET doesn't
 		{"/!invalid!", http.StatusBadRequest}, // has non-base62 chars
 	}
 	for _, tt := range tests {