feat: add copy/duplicate trip from dashboard (#270)

New POST /api/trips/:id/copy endpoint that deep copies all trip
planning data (days, places, assignments, reservations, budget,
packing, accommodations, day notes) with proper FK remapping
inside a transaction. Skips files, collab data, and members.

Copy button on all dashboard card types (spotlight, grid, list,
archived) gated by trip_create permission. Translations for all
12 languages.

Also adds reminder_days to Trip interface (removes as-any casts).

client/src/i18n/translations/ar.ts

@@ -87,6 +87,8 @@ const ar: Record<string, string | { name: string; category: string }[]> = {
   'dashboard.places': 'الأماكن',
   'dashboard.members': 'ال חברים',
   'dashboard.archive': 'أرشفة',
+  'dashboard.copyTrip': 'نسخ',
+  'dashboard.copySuffix': 'نسخة',
   'dashboard.restore': 'استعادة',
   'dashboard.archived': 'مؤرشفة',
   'dashboard.status.ongoing': 'جارية',
@@ -105,6 +107,8 @@ const ar: Record<string, string | { name: string; category: string }[]> = {
   'dashboard.toast.archiveError': 'فشل الأرشفة',
   'dashboard.toast.restored': 'تمت استعادة الرحلة',
   'dashboard.toast.restoreError': 'فشل الاستعادة',
+  'dashboard.toast.copied': 'تم نسخ الرحلة!',
+  'dashboard.toast.copyError': 'فشل نسخ الرحلة',
   'dashboard.confirm.delete': 'حذف الرحلة "{title}"؟ سيتم حذف جميع الأماكن والخطط نهائيًا.',
   'dashboard.editTrip': 'تعديل الرحلة',
   'dashboard.createTrip': 'إنشاء رحلة جديدة',