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/i18n/dictionaries/en.ts

@@ -26,6 +26,19 @@ const en: Dictionary = {
     currencyShort: 'T',
   },
 
+  errors: {
+    generic: 'Something went wrong. Please try again.',
+    network: 'Could not reach the server. Check your internet connection.',
+    timeout: 'The server took too long to respond. Please try again.',
+    unauthorized: 'Your session has expired. Please sign in again.',
+    forbidden: 'You do not have permission to do this.',
+    notFound: 'The requested item was not found.',
+    conflict: 'This action conflicts with the current state. Refresh and try again.',
+    validation: 'The information you entered is invalid. Please check your input.',
+    rateLimit: 'Too many requests. Please wait a moment and try again.',
+    server: 'A server error occurred. Please try again shortly.',
+  },
+
   language: {
     label: 'Language',
   },
@@ -1080,7 +1093,7 @@ const en: Dictionary = {
       upgradedPaid: 'Resources upgraded! Paid {amount} Toman',
       upgradeFailed: 'Failed to upgrade resources', calcFailed: 'Failed to calculate upgrade cost',
       invoiceCreated: 'Invoice created. Choose how you want to pay.', invoiceFailed: 'Failed to create upgrade invoice',
-      dbRestored: 'Database restored successfully!', dbInvalidFile: 'Please upload a .sql, .dump, or .gz file',
+      dbRestored: 'Database restored successfully!', dbRestoreFailed: 'Database restore failed.', dbInvalidFile: 'Please upload a .sql, .dump, or .gz file',
       fileMax500: 'File size must be less than 500MB', dbUploadFailed: 'Failed to upload database dump',
       snapshotStarted: 'Snapshot creation started', snapshotCreateFailed: 'Failed to create snapshot',
       snapshotDeleted: 'Snapshot deleted', snapshotDeleteFailed: 'Failed to delete snapshot',