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/api/client.ts

@@ -83,6 +83,7 @@ export const tripsApi = {
   getMembers: (id: number | string) => apiClient.get(`/trips/${id}/members`).then(r => r.data),
   addMember: (id: number | string, identifier: string) => apiClient.post(`/trips/${id}/members`, { identifier }).then(r => r.data),
   removeMember: (id: number | string, userId: number) => apiClient.delete(`/trips/${id}/members/${userId}`).then(r => r.data),
+  copy: (id: number | string, data?: { title?: string }) => apiClient.post(`/trips/${id}/copy`, data || {}).then(r => r.data),
 }
 
 export const daysApi = {