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

server/src/index.js

@@ -57,6 +57,7 @@ app.use('/uploads', express.static(path.join(__dirname, '../uploads')));
 const authRoutes = require('./routes/auth');
 const tripsRoutes = require('./routes/trips');
 const daysRoutes = require('./routes/days');
+const accommodationsRoutes = require('./routes/days').accommodationsRouter;
 const placesRoutes = require('./routes/places');
 const assignmentsRoutes = require('./routes/assignments');
 const packingRoutes = require('./routes/packing');
@@ -77,6 +78,7 @@ app.use('/api/auth', authRoutes);
 app.use('/api/auth/oidc', oidcRoutes);
 app.use('/api/trips', tripsRoutes);
 app.use('/api/trips/:tripId/days', daysRoutes);
+app.use('/api/trips/:tripId/accommodations', accommodationsRoutes);
 app.use('/api/trips/:tripId/places', placesRoutes);
 app.use('/api/trips/:tripId/packing', packingRoutes);
 app.use('/api/trips/:tripId/files', filesRoutes);