add path param lure customization

Signed-off-by: RonniSkansing <rskansing@gmail.com>

backend/api/response.go

@@ -42,6 +42,7 @@ type JSONResponseHandler interface {
 	Forbidden(g *gin.Context)
 	BadRequest(g *gin.Context)
 	BadRequestMessage(g *gin.Context, message string)
+	Conflict(g *gin.Context, message string, data any)
 	ValidationFailed(g *gin.Context, field string, err error)
 	ServerError(g *gin.Context)
 	ServerErrorMessage(g *gin.Context, message string)
@@ -130,6 +131,17 @@ func (r *jsonResponseHandler) BadRequestMessage(g *gin.Context, message string)
 	g.Abort()
 }
 
+// Conflict responds with 409 - CONFLICT and carries enough detail for the
+// caller to offer a resolution, such as naming the campaign already holding a
+// lure code the operator asked for.
+func (r *jsonResponseHandler) Conflict(g *gin.Context, message string, data any) {
+	g.JSON(
+		http.StatusConflict,
+		r.newResponse(false, data, message),
+	)
+	g.Abort()
+}
+
 func (r *jsonResponseHandler) unwrapErrorMessage(err error) string {
 	message := err.Error()
 	unwrapped := errors.Unwrap(err)