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/components/managed-database-config.tsx

@@ -2,7 +2,7 @@
 
 import { useRef, useState } from 'react';
 import { Database, Eye, EyeOff, RefreshCw, AlertCircle } from 'lucide-react';
-import { toast } from 'react-toastify';
+import { notify } from '@/lib/notify';
 import { useT } from '@/i18n/I18nProvider';
 import { Select } from '@/components/ui/select';
 import { ONE_GIB, minGiToFitFileBytes } from '@/lib/storage-utils';
@@ -57,11 +57,11 @@ export function ManagedDatabaseConfig({
 
   const acceptDump = (f: File) => {
     if (!f.name.endsWith('.sql') && !f.name.endsWith('.gz') && !f.name.endsWith('.dump')) {
-      toast.error(c.allowedFormats);
+      notify.error(c.allowedFormats);
       return;
     }
     if (f.size > 500 * 1024 * 1024) {
-      toast.error(c.maxSize);
+      notify.error(c.maxSize);
       return;
     }
     onDbDumpFileChange(f);