feat(inboxes): enforce chatwoot inbox limits

internal/handler/api/v1/inbox_handler.go

@@ -134,6 +134,9 @@ func (h *InboxHandler) Create(c *gin.Context) {
 
 	inbox, svcErr := h.svc.Create(c.Request.Context(), accountID, req)
 	if svcErr != nil {
+		if renderInboxLimitExceeded(c, svcErr) {
+			return
+		}
 		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": "failed to create inbox"})
 		return
 	}
@@ -239,6 +242,14 @@ func (h *InboxHandler) Delete(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"message": "Your inbox deletion request will be processed in some time."})
 }
 
+func renderInboxLimitExceeded(c *gin.Context, err error) bool {
+	if !service.IsInboxLimitExceeded(err) {
+		return false
+	}
+	c.JSON(http.StatusPaymentRequired, gin.H{"error": service.InboxLimitExceededMessage})
+	return true
+}
+
 func bindCreateInboxRequest(c *gin.Context, req *service.CreateInboxRequest) error {
 	if strings.Contains(c.ContentType(), "json") {
 		return bindCreateInboxJSON(c, req)