v2.5.7: Reservation overhaul, Day Detail Panel, i18n, paste support, auto dark mode

BREAKING: Reservations have been completely rebuilt. Existing place-level
reservations are no longer used. All reservations must be re-created via
the Bookings tab. Your trips, places, and other data are unaffected.

Reservation System (rebuilt from scratch):
- Reservations now link to specific day assignments instead of places
- Same place on different days can have independent reservations
- New assignment picker in booking modal (grouped by day, searchable)
- Removed day/place dropdowns from booking form
- Reservation badges in day plan sidebar with type-specific icons
- Reservation details in place inspector (only for selected assignment)
- Reservation summary in day detail panel

Day Detail Panel (new):
- Opens on day click in the sidebar
- Detailed weather: hourly forecast, precipitation, wind, sunrise/sunset
- Historical climate averages for dates beyond 16 days
- Accommodation management with check-in/check-out, confirmation number
- Hotel assignment across multiple days with day range picker
- Reservation overview for the day

Places:
- Places can now be assigned to the same day multiple times
- Start time + end time fields (replaces single time field)
- Map badges show multiple position numbers (e.g. "1 · 4")
- Route optimization fixed for duplicate places
- File attachments during place editing (not just creation)
- Cover image upload during trip creation (not just editing)
- Paste support (Ctrl+V) for images in trip, place, and file forms

Internationalization:
- 200+ hardcoded German strings translated to i18n (EN + DE)
- Server error messages in English
- Category seeds in English for new installations
- All planner, register, photo, packing components translated

UI/UX:
- Auto dark mode (follows system preference, configurable in settings)
- Navbar toggle switches light/dark (overrides auto)
- Sidebar minimize buttons z-index fixed
- Transport mode selector removed from day plan
- CustomSelect supports grouped headers (isHeader option)
- Optimistic updates for day notes (instant feedback)
- Booking cards redesigned with type-colored headers and structured details

Weather:
- Wind speed in mph when using Fahrenheit setting
- Weather description language matches app language

Admin:
- Weather info panel replaces OpenWeatherMap key input
- "Recommended" badge styling updated

client/src/api/client.js

@@ -94,6 +94,7 @@ export const assignmentsApi = {
   delete: (tripId, dayId, id) => apiClient.delete(`/trips/${tripId}/days/${dayId}/assignments/${id}`).then(r => r.data),
   reorder: (tripId, dayId, orderedIds) => apiClient.put(`/trips/${tripId}/days/${dayId}/assignments/reorder`, { orderedIds }).then(r => r.data),
   move: (tripId, assignmentId, newDayId, orderIndex) => apiClient.put(`/trips/${tripId}/assignments/${assignmentId}/move`, { new_day_id: newDayId, order_index: orderIndex }).then(r => r.data),
+  update: (tripId, dayId, id, data) => apiClient.put(`/trips/${tripId}/days/${dayId}/assignments/${id}`, data).then(r => r.data),
 }
 
 export const packingApi = {
@@ -168,6 +169,7 @@ export const reservationsApi = {
 
 export const weatherApi = {
   get: (lat, lng, date) => apiClient.get('/weather', { params: { lat, lng, date } }).then(r => r.data),
+  getDetailed: (lat, lng, date, lang) => apiClient.get('/weather/detailed', { params: { lat, lng, date, lang } }).then(r => r.data),
 }
 
 export const settingsApi = {
@@ -176,6 +178,13 @@ export const settingsApi = {
   setBulk: (settings) => apiClient.post('/settings/bulk', { settings }).then(r => r.data),
 }
 
+export const accommodationsApi = {
+  list: (tripId) => apiClient.get(`/trips/${tripId}/accommodations`).then(r => r.data),
+  create: (tripId, data) => apiClient.post(`/trips/${tripId}/accommodations`, data).then(r => r.data),
+  update: (tripId, id, data) => apiClient.put(`/trips/${tripId}/accommodations/${id}`, data).then(r => r.data),
+  delete: (tripId, id) => apiClient.delete(`/trips/${tripId}/accommodations/${id}`).then(r => r.data),
+}
+
 export const dayNotesApi = {
   list: (tripId, dayId) => apiClient.get(`/trips/${tripId}/days/${dayId}/notes`).then(r => r.data),
   create: (tripId, dayId, data) => apiClient.post(`/trips/${tripId}/days/${dayId}/notes`, data).then(r => r.data),
@@ -191,7 +200,7 @@ export const backupApi = {
     const res = await fetch(`/api/backup/download/${filename}`, {
       headers: { Authorization: `Bearer ${token}` },
     })
-    if (!res.ok) throw new Error('Download fehlgeschlagen')
+    if (!res.ok) throw new Error('Download failed')
     const blob = await res.blob()
     const url = URL.createObjectURL(blob)
     const a = document.createElement('a')