feat: add client-side permission gating to all write-action UIs

Gate all mutating UI elements with useCanDo() permission checks:
- BudgetPanel (budget_edit), PackingListPanel (packing_edit)
- DayPlanSidebar, DayDetailPanel (day_edit)
- ReservationsPanel, ReservationModal (reservation_edit)
- CollabNotes, CollabPolls, CollabChat (collab_edit)
- FileManager (file_edit, file_delete, file_upload)
- PlaceFormModal, PlaceInspector, PlacesSidebar (place_edit, file_upload)
- TripFormModal (trip_edit, trip_cover_upload)
- DashboardPage (trip_edit, trip_cover_upload, trip_delete, trip_archive)
- TripMembersModal (member_manage, share_manage)

Also: fix redundant getTripOwnerId queries in trips.ts, remove dead
getTripOwnerId function, fix TripMembersModal grid when share hidden,
fix canRemove logic, guard TripListItem empty actions div.

client/src/pages/DashboardPage.tsx

@@ -410,7 +410,7 @@ function TripListItem({ trip, onEdit, onDelete, onArchive, onClick, t, locale, i
       </div>
 
       {/* Actions */}
-      {(!!trip.is_owner || isAdmin) && (
+      {(onEdit || onArchive || onDelete) && (
       <div style={{ display: 'flex', gap: 4, flexShrink: 0 }} onClick={e => e.stopPropagation()}>
         {onEdit && <CardAction onClick={() => onEdit(trip)} icon={<Edit2 size={12} />} label="" />}
         {onArchive && <CardAction onClick={() => onArchive(trip.id)} icon={<Archive size={12} />} label="" />}

client/src/pages/TripPlannerPage.tsx

@@ -2,6 +2,7 @@ import React, { useState, useEffect, useCallback, useMemo } from 'react'
 import ReactDOM from 'react-dom'
 import { useParams, useNavigate } from 'react-router-dom'
 import { useTripStore } from '../store/tripStore'
+import { useCanDo } from '../store/permissionsStore'
 import { useSettingsStore } from '../store/settingsStore'
 import { MapView } from '../components/Map/MapView'
 import DayPlanSidebar from '../components/Planner/DayPlanSidebar'
@@ -38,6 +39,8 @@ export default function TripPlannerPage(): React.ReactElement | null {
   const { settings } = useSettingsStore()
   const tripStore = useTripStore()
   const { trip, days, places, assignments, packingItems, categories, reservations, budgetItems, files, selectedDayId, isLoading } = tripStore
+  const can = useCanDo()
+  const canUploadFiles = can('file_upload', trip)
 
   const [enabledAddons, setEnabledAddons] = useState<Record<string, boolean>>({ packing: true, budget: true, documents: true })
   const [tripAccommodations, setTripAccommodations] = useState<Accommodation[]>([])
@@ -584,7 +587,7 @@ export default function TripPlannerPage(): React.ReactElement | null {
                 onAssignToDay={handleAssignToDay}
                 onRemoveAssignment={handleRemoveAssignment}
                 files={files}
-                onFileUpload={(fd) => tripStore.addFile(tripId, fd)}
+                onFileUpload={canUploadFiles ? (fd) => tripStore.addFile(tripId, fd) : undefined}
                 tripMembers={tripMembers}
                 onSetParticipants={async (assignmentId, dayId, userIds) => {
                   try {
@@ -688,7 +691,7 @@ export default function TripPlannerPage(): React.ReactElement | null {
       <PlaceFormModal isOpen={showPlaceForm} onClose={() => { setShowPlaceForm(false); setEditingPlace(null); setEditingAssignmentId(null); setPrefillCoords(null) }} onSave={handleSavePlace} place={editingPlace} prefillCoords={prefillCoords} assignmentId={editingAssignmentId} dayAssignments={editingAssignmentId ? Object.values(assignments).flat() : []} tripId={tripId} categories={categories} onCategoryCreated={cat => tripStore.addCategory?.(cat)} />
       <TripFormModal isOpen={showTripForm} onClose={() => setShowTripForm(false)} onSave={async (data) => { await tripStore.updateTrip(tripId, data); toast.success(t('trip.toast.tripUpdated')) }} trip={trip} />
       <TripMembersModal isOpen={showMembersModal} onClose={() => setShowMembersModal(false)} tripId={tripId} tripTitle={trip?.title} />
-      <ReservationModal isOpen={showReservationModal} onClose={() => { setShowReservationModal(false); setEditingReservation(null) }} onSave={handleSaveReservation} reservation={editingReservation} days={days} places={places} assignments={assignments} selectedDayId={selectedDayId} files={files} onFileUpload={(fd) => tripStore.addFile(tripId, fd)} onFileDelete={(id) => tripStore.deleteFile(tripId, id)} accommodations={tripAccommodations} />
+      <ReservationModal isOpen={showReservationModal} onClose={() => { setShowReservationModal(false); setEditingReservation(null) }} onSave={handleSaveReservation} reservation={editingReservation} days={days} places={places} assignments={assignments} selectedDayId={selectedDayId} files={files} onFileUpload={canUploadFiles ? (fd) => tripStore.addFile(tripId, fd) : undefined} onFileDelete={(id) => tripStore.deleteFile(tripId, id)} accommodations={tripAccommodations} />
       <ConfirmDialog
         isOpen={!!deletePlaceId}
         onClose={() => setDeletePlaceId(null)}