feat(api): surface backend error messages globally via toast

Show the backend's Persian error (errors[0].message, e.g. rate-limit
'درخواست‌های زیاد') as a toast for any failed request.* call, from the
axios response interceptor — so failures are no longer silent. 401 still
logs out/redirects without a toast; callers can opt out with
config.skipErrorToast. Drop now-redundant per-caller alerts/toasts in
the booking submit, payment, and OTP userinfo paths.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

components/appointment/detail/SubmitData.js

@@ -127,7 +127,6 @@ function SubmitData({ setStep, data, prevData, setErrors, doctor, isForAnother,
     } catch (error) {
       setLoading(false);
       if (error?.response?.status === 409) {
-        alert("این زمان همین لحظه توسط کاربر دیگری رزرو شد. لطفاً ساعت دیگری انتخاب کنید.");
         setStep(0);
         return;
       }

components/appointment/paying/index.js

@@ -63,7 +63,6 @@ function Paying({ setStep, appointmentId, expiresAt, doctor, selectedSlot, selec
       }
     } catch (error) {
       console.error("Payment error:", error);
-      alert("خطا در پرداخت");
       setLoading(false);
     }
   };

components/register/verificationPage/SendReq.js

@@ -103,7 +103,6 @@ function SendReq({
       .catch(() => {
         setLoading(false);
         setIsError(true);
-        toast.error("دریافت اطلاعات کاربر ناموفق بود. دوباره تلاش کنید.");
       });
   };
 

services/api.js

@@ -1,5 +1,17 @@
 import axios from "axios";
 import Cookies from "js-cookie";
+import { toast } from "react-toastify";
+
+function extractErrorMessage(error) {
+  const errors = error?.response?.data?.errors;
+  if (Array.isArray(errors) && errors.length > 0 && errors[0]?.message) {
+    return errors[0].message;
+  }
+  if (error?.response?.data?.message) {
+    return error.response.data.message;
+  }
+  return "خطایی رخ داد. لطفاً دوباره تلاش کنید.";
+}
 
 const BASE_URL = process.env.NEXT_PUBLIC_API_URL;
 
@@ -33,16 +45,20 @@ api.interceptors.response.use(
     return response.data;
   },
   (error) => {
-    if (error?.response?.status === 401 && typeof window !== "undefined") {
-      const hostname = window.location.hostname;
-      const domain = hostname.includes("localhost")
-        ? undefined
-        : `.${hostname.split(".").slice(-2).join(".")}`;
-      const opts = { path: "/", ...(domain && { domain }) };
-      ["access_token", "refresh_token", "uuid", "userInfo"].forEach((key) => {
-        Cookies.remove(key, opts);
-      });
-      window.location.href = "/login";
+    if (typeof window !== "undefined") {
+      if (error?.response?.status === 401) {
+        const hostname = window.location.hostname;
+        const domain = hostname.includes("localhost")
+          ? undefined
+          : `.${hostname.split(".").slice(-2).join(".")}`;
+        const opts = { path: "/", ...(domain && { domain }) };
+        ["access_token", "refresh_token", "uuid", "userInfo"].forEach((key) => {
+          Cookies.remove(key, opts);
+        });
+        window.location.href = "/login";
+      } else if (!error?.config?.skipErrorToast) {
+        toast.error(extractErrorMessage(error));
+      }
     }
     return Promise.reject(error);
   }