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/pages/RegisterPage.jsx

@@ -1,9 +1,11 @@
 import React, { useState } from 'react'
 import { Link, useNavigate } from 'react-router-dom'
 import { useAuthStore } from '../store/authStore'
+import { useTranslation } from '../i18n'
 import { Map, Eye, EyeOff, Mail, Lock, User } from 'lucide-react'
 
 export default function RegisterPage() {
+  const { t } = useTranslation()
   const [username, setUsername] = useState('')
   const [email, setEmail] = useState('')
   const [password, setPassword] = useState('')
@@ -20,12 +22,12 @@ export default function RegisterPage() {
     setError('')
 
     if (password !== confirmPassword) {
-      setError('Passwörter stimmen nicht überein')
+      setError(t('register.passwordMismatch'))
       return
     }
 
     if (password.length < 6) {
-      setError('Passwort muss mindestens 6 Zeichen lang sein')
+      setError(t('register.passwordTooShort'))
       return
     }
 
@@ -34,7 +36,7 @@ export default function RegisterPage() {
       await register(username, email, password)
       navigate('/dashboard')
     } catch (err) {
-      setError(err.message || 'Registrierung fehlgeschlagen')
+      setError(err.message || t('register.failed'))
     } finally {
       setIsLoading(false)
     }
@@ -48,19 +50,19 @@ export default function RegisterPage() {
           <div className="w-20 h-20 bg-white/10 rounded-2xl flex items-center justify-center mx-auto mb-6">
             <Map className="w-10 h-10 text-white" />
           </div>
-          <h1 className="text-4xl font-bold mb-4">Jetzt starten</h1>
+          <h1 className="text-4xl font-bold mb-4">{t('register.getStarted')}</h1>
           <p className="text-slate-300 text-lg leading-relaxed">
-            Erstellen Sie ein Konto und beginnen Sie, Ihre Traumreisen zu planen.
+            {t('register.subtitle')}
           </p>
 
           <div className="mt-10 space-y-3 text-left">
             {[
-              '✓ Unbegrenzte Reisepläne',
-              '✓ Interaktive Kartenansicht',
-              '✓ Orte und Kategorien verwalten',
-              '✓ Reservierungen tracken',
-              '✓ Packlisten erstellen',
-              '✓ Fotos und Dateien speichern',
+              `✓ ${t('register.feature1')}`,
+              `✓ ${t('register.feature2')}`,
+              `✓ ${t('register.feature3')}`,
+              `✓ ${t('register.feature4')}`,
+              `✓ ${t('register.feature5')}`,
+              `✓ ${t('register.feature6')}`,
             ].map(item => (
               <p key={item} className="text-slate-200 text-sm">{item}</p>
             ))}
@@ -77,8 +79,8 @@ export default function RegisterPage() {
           </div>
 
           <div className="bg-white rounded-2xl shadow-sm border border-slate-200 p-8">
-            <h2 className="text-2xl font-bold text-slate-900 mb-1">Konto erstellen</h2>
-            <p className="text-slate-500 mb-8">Beginnen Sie Ihre Reiseplanung</p>
+            <h2 className="text-2xl font-bold text-slate-900 mb-1">{t('register.createAccount')}</h2>
+            <p className="text-slate-500 mb-8">{t('register.startPlanning')}</p>
 
             <form onSubmit={handleSubmit} className="space-y-5">
               {error && (
@@ -88,7 +90,7 @@ export default function RegisterPage() {
               )}
 
               <div>
-                <label className="block text-sm font-medium text-slate-700 mb-1.5">Benutzername</label>
+                <label className="block text-sm font-medium text-slate-700 mb-1.5">{t('settings.username')}</label>
                 <div className="relative">
                   <User className="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-slate-400" />
                   <input
@@ -96,7 +98,7 @@ export default function RegisterPage() {
                     value={username}
                     onChange={e => setUsername(e.target.value)}
                     required
-                    placeholder="maxmustermann"
+                    placeholder="johndoe"
                     minLength={3}
                     className="w-full pl-10 pr-4 py-2.5 border border-slate-300 rounded-lg text-slate-900 placeholder-slate-400 focus:ring-2 focus:ring-slate-400 focus:border-transparent transition-all"
                   />
@@ -104,7 +106,7 @@ export default function RegisterPage() {
               </div>
 
               <div>
-                <label className="block text-sm font-medium text-slate-700 mb-1.5">E-Mail</label>
+                <label className="block text-sm font-medium text-slate-700 mb-1.5">{t('common.email')}</label>
                 <div className="relative">
                   <Mail className="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-slate-400" />
                   <input
@@ -112,14 +114,14 @@ export default function RegisterPage() {
                     value={email}
                     onChange={e => setEmail(e.target.value)}
                     required
-                    placeholder="ihre@email.de"
+                    placeholder="your@email.com"
                     className="w-full pl-10 pr-4 py-2.5 border border-slate-300 rounded-lg text-slate-900 placeholder-slate-400 focus:ring-2 focus:ring-slate-400 focus:border-transparent transition-all"
                   />
                 </div>
               </div>
 
               <div>
-                <label className="block text-sm font-medium text-slate-700 mb-1.5">Passwort</label>
+                <label className="block text-sm font-medium text-slate-700 mb-1.5">{t('common.password')}</label>
                 <div className="relative">
                   <Lock className="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-slate-400" />
                   <input
@@ -127,7 +129,7 @@ export default function RegisterPage() {
                     value={password}
                     onChange={e => setPassword(e.target.value)}
                     required
-                    placeholder="Mind. 6 Zeichen"
+                    placeholder={t('register.minChars')}
                     className="w-full pl-10 pr-12 py-2.5 border border-slate-300 rounded-lg text-slate-900 placeholder-slate-400 focus:ring-2 focus:ring-slate-400 focus:border-transparent transition-all"
                   />
                   <button
@@ -141,7 +143,7 @@ export default function RegisterPage() {
               </div>
 
               <div>
-                <label className="block text-sm font-medium text-slate-700 mb-1.5">Passwort bestätigen</label>
+                <label className="block text-sm font-medium text-slate-700 mb-1.5">{t('register.confirmPassword')}</label>
                 <div className="relative">
                   <Lock className="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-slate-400" />
                   <input
@@ -149,7 +151,7 @@ export default function RegisterPage() {
                     value={confirmPassword}
                     onChange={e => setConfirmPassword(e.target.value)}
                     required
-                    placeholder="Passwort wiederholen"
+                    placeholder={t('register.repeatPassword')}
                     className="w-full pl-10 pr-4 py-2.5 border border-slate-300 rounded-lg text-slate-900 placeholder-slate-400 focus:ring-2 focus:ring-slate-400 focus:border-transparent transition-all"
                   />
                 </div>
@@ -163,17 +165,17 @@ export default function RegisterPage() {
                 {isLoading ? (
                   <>
                     <div className="w-4 h-4 border-2 border-white/30 border-t-white rounded-full animate-spin"></div>
-                    Registrieren...
+                    {t('register.registering')}
                   </>
-                ) : 'Registrieren'}
+                ) : t('register.register')}
               </button>
             </form>
 
             <div className="mt-6 text-center">
               <p className="text-sm text-slate-500">
-                Bereits ein Konto?{' '}
+                {t('register.hasAccount')}{' '}
                 <Link to="/login" className="text-slate-900 hover:text-slate-700 font-medium">
-                  Anmelden
+                  {t('register.signIn')}
                 </Link>
               </p>
             </div>