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/nl.ts

@@ -82,6 +82,8 @@ const nl: Record<string, string> = {
   'dashboard.places': 'Plaatsen',
   'dashboard.members': 'Reisgenoten',
   'dashboard.archive': 'Archiveren',
+  'dashboard.copyTrip': 'Kopiëren',
+  'dashboard.copySuffix': 'kopie',
   'dashboard.restore': 'Herstellen',
   'dashboard.archived': 'Gearchiveerd',
   'dashboard.status.ongoing': 'Lopend',
@@ -100,6 +102,8 @@ const nl: Record<string, string> = {
   'dashboard.toast.archiveError': 'Reis archiveren mislukt',
   'dashboard.toast.restored': 'Reis hersteld',
   'dashboard.toast.restoreError': 'Reis herstellen mislukt',
+  'dashboard.toast.copied': 'Reis gekopieerd!',
+  'dashboard.toast.copyError': 'Reis kopiëren mislukt',
   'dashboard.confirm.delete': 'Reis "{title}" verwijderen? Alle plaatsen en plannen worden permanent verwijderd.',
   'dashboard.editTrip': 'Reis bewerken',
   'dashboard.createTrip': 'Nieuwe reis aanmaken',