Restyle toasts and centralize friendly error handling.

Replace the default react-toastify look with project-styled toast cards
(icon chip, rounded shell, RTL-aware container, type-colored progress
bar) via a new notify helper and globals.css overrides.

Add a central error layer (src/lib/errors.ts): classify any caught error
by HTTP status / network condition, log the full technical detail
(including the raw backend message) to the console only, and surface a
friendly, localized message to the user. Raw backend messages are no
longer shown. All ~190 toast call sites across 22 files move to notify,
routing backend errors through notify.error(err, fallback); dead
apiErrorMessage/formatApiError helpers removed. Adds an `errors` section
to the fa/en dictionaries.

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

frontend/src/app/[lang]/dashboard/admin/billing/page.tsx

@@ -3,7 +3,7 @@
 import { useState, useEffect } from 'react';
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
 import api from '@/lib/api';
-import { toast } from 'react-toastify';
+import { notify } from '@/lib/notify';
 import { useT } from '@/i18n/I18nProvider';
 import type {
   PricingCatalog,
@@ -39,15 +39,6 @@ function toPricingCatalogPatch(catalog: PricingCatalog) {
   };
 }
 
-function formatApiError(err: unknown, fallback: string): string {
-  if (!err || typeof err !== 'object' || !('response' in err)) return fallback;
-  const message = (err as { response?: { data?: { message?: string | string[] } } }).response
-    ?.data?.message;
-  if (Array.isArray(message)) return message.join(', ');
-  if (typeof message === 'string') return message;
-  return fallback;
-}
-
 function cloneCatalog(catalog: PricingCatalog): PricingCatalog {
   const runtimes: PricingCatalog['runtimes'] = {};
   for (const key of Object.keys(catalog.runtimes)) {
@@ -377,12 +368,12 @@ export default function AdminBillingPage() {
       queryClient.invalidateQueries({ queryKey: ['pricing-catalog'] });
       queryClient.invalidateQueries({ queryKey: ['custom-domain-price'] });
       queryClient.invalidateQueries({ queryKey: ['optional-services-pricing'] });
-      toast.success(b.saved);
+      notify.success(b.saved);
       setEditing(false);
       setDraft(null);
     },
     onError: (err: unknown) => {
-      toast.error(formatApiError(err, b.saveFailed));
+      notify.error(err, b.saveFailed);
     },
   });
 
@@ -743,11 +734,11 @@ function LifecycleSettingsSection() {
     mutationFn: (body: Record<string, number>) => api.patch('/lifecycle/settings', body),
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['lifecycle-settings'] });
-      toast.success(b.lifecycleSaved);
+      notify.success(b.lifecycleSaved);
       setEditing(false);
     },
     onError: (err: unknown) => {
-      toast.error(formatApiError(err, b.saveFailedShort));
+      notify.error(err, b.saveFailedShort);
     },
   });