Reorder whole days and insert a day (#589) (#1148)

* feat(days): reorder whole days and insert a day at a position

Adds reorderDays + insertDay to the day service and a PUT /days/reorder route
(plus an optional position on create). Day rows stay stable so a day's
assignments, notes, bookings and accommodations ride along by id; on a dated
trip the calendar dates stay pinned to their slots while the content moves
across them, and each booking's date is re-stamped onto its day's new date
(time-of-day preserved) so day_id stays consistent. Renumbering uses the
two-phase write to avoid the UNIQUE(trip_id, day_number) collision, and a move
that would invert an accommodation's check-in/out span is rejected.

* feat(planner): reorder days from a toolbar popup, and add days

A new toolbar button opens a popup listing the days; drag a row by its grip or
use the up/down arrows to reorder, and add a day from there. Reorders apply
optimistically with rollback and sync over WebSocket; the day headers are left
untouched, so the existing place drop-targets are unaffected.

* i18n: add day-reorder strings across all languages

client/src/store/tripStore.ts

@@ -9,6 +9,7 @@ import { packingRepo } from '../repo/packingRepo'
 import { todoRepo } from '../repo/todoRepo'
 import { createPlacesSlice } from './slices/placesSlice'
 import { createAssignmentsSlice } from './slices/assignmentsSlice'
+import { createDaysSlice } from './slices/daysSlice'
 import { createDayNotesSlice } from './slices/dayNotesSlice'
 import { createPackingSlice } from './slices/packingSlice'
 import { createTodoSlice } from './slices/todoSlice'
@@ -24,6 +25,7 @@ import type {
 import { getApiErrorMessage } from '../types'
 import type { PlacesSlice } from './slices/placesSlice'
 import type { AssignmentsSlice } from './slices/assignmentsSlice'
+import type { DaysSlice } from './slices/daysSlice'
 import type { DayNotesSlice } from './slices/dayNotesSlice'
 import type { PackingSlice } from './slices/packingSlice'
 import type { TodoSlice } from './slices/todoSlice'
@@ -34,6 +36,7 @@ import type { FilesSlice } from './slices/filesSlice'
 export interface TripStoreState
   extends PlacesSlice,
     AssignmentsSlice,
+    DaysSlice,
     DayNotesSlice,
     PackingSlice,
     TodoSlice,
@@ -184,6 +187,7 @@ export const useTripStore = create<TripStoreState>((set, get) => ({
 
   ...createPlacesSlice(set, get),
   ...createAssignmentsSlice(set, get),
+  ...createDaysSlice(set, get),
   ...createDayNotesSlice(set, get),
   ...createPackingSlice(set, get),
   ...createTodoSlice(set, get),