fix(mobile): offer the currency on the dashboard trip sheet

The mobile create/edit sheet never showed the currency, so every trip
started from the dashboard silently took the server default of EUR and
could only be corrected from the trip planner, which reuses TripFormModal
and does have the field.

Same control as the desktop form — searchable select over currenciesWith(),
gated on trip_edit like the rest of the sheet.

client/src/mobile/screens/dashboard/MNewTripSheet.tsx

@@ -7,6 +7,8 @@ import { useToast } from '../../../components/shared/Toast'
 import { normalizeImageFile } from '../../../utils/convertHeic'
 import { getApiErrorMessage } from '../../../types'
 import { CustomDatePicker } from '../../../components/shared/CustomDateTimePicker'
+import CustomSelect from '../../../components/shared/CustomSelect'
+import { currenciesWith, SYMBOLS } from '../../../components/Budget/BudgetPanel.constants'
 import type { DashboardTrip } from '../../../pages/dashboard/dashboardModel'
 import type { Trip, TripCreateRequest } from '@trek/shared'
 import MSheet from '../../components/MSheet'
@@ -57,6 +59,7 @@ export default function MNewTripSheet({ open, trip, onClose, onSave, onCoverUpda
   const [description, setDescription] = useState('')
   const [startDate, setStartDate] = useState('')
   const [endDate, setEndDate] = useState('')
+  const [currency, setCurrency] = useState('EUR')
   const [error, setError] = useState('')
   const [isSaving, setIsSaving] = useState(false)
   const [coverPreview, setCoverPreview] = useState<string | null>(null)
@@ -74,6 +77,7 @@ export default function MNewTripSheet({ open, trip, onClose, onSave, onCoverUpda
     setDescription(trip?.description || '')
     setStartDate(trip?.start_date || '')
     setEndDate(trip?.end_date || '')
+    setCurrency(trip?.currency || 'EUR')
     setCoverPreview(trip?.cover_image || null)
     setPendingCoverFile(null)
     setPendingUnsplashUrl(null)
@@ -109,6 +113,7 @@ export default function MNewTripSheet({ open, trip, onClose, onSave, onCoverUpda
         description: description.trim() || null,
         start_date: startDate || null,
         end_date: endDate || null,
+        currency,
         ...(!startDate && !endDate && !isEditing ? { day_count: 7 } : {}),
       })
       const created = result ? result.trip : undefined
@@ -290,6 +295,19 @@ export default function MNewTripSheet({ open, trip, onClose, onSave, onCoverUpda
           <div className="mt-[6px] px-1 font-geist text-[0.625rem] text-m-faint">{t('dashboard.noDateHint')}</div>
         )}
 
+        <div className="mt-2">
+          <FieldLabel>{t('dashboard.currency')}</FieldLabel>
+          <CustomSelect
+            value={currency}
+            onChange={v => { if (canEditTrip) setCurrency(String(v)) }}
+            disabled={!canEditTrip}
+            searchable
+            size="sm"
+            options={currenciesWith(currency).map(c => ({ value: c, label: `${c} (${SYMBOLS[c] || c})` }))}
+            style={{ width: '100%', marginTop: 5 }}
+          />
+        </div>
+
         {canUploadCover && (
           <div className="mt-2">
             <input