security: A01-13 — nest all event routes under organisation prefix

Move all authenticated organiser-facing event sub-resource routes from
/events/{event}/... to /organisations/{organisation}/events/{event}/...
to enforce multi-tenancy at the routing layer.

Changes:
- Routes: restructured api.php to nest all event sub-resources under
  the existing organisation prefix group
- Controllers: added Organisation parameter and VerifiesOrganisationEvent
  trait to all 12 affected controllers (sections, time-slots, shifts,
  persons, crowd-lists, locations, shift-assignments, registration-fields,
  availabilities, field-values, section-preferences, stats)
- Tests: updated all 20 feature test files with new route paths
- Frontend: updated 8 API composables and 20 Vue components/pages
- API.md: updated documentation to reflect new route structure

Portal routes, public routes (volunteer-register), and invitation routes
remain unchanged as they operate without organisation context.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/app/src/components/sections/CreateShiftDialog.vue

@@ -2,6 +2,7 @@
 import { VForm } from 'vuetify/components/VForm'
 import { useCreateShift, useUpdateShift } from '@/composables/api/useShifts'
 import { useTimeSlotList } from '@/composables/api/useTimeSlots'
+import { useAuthStore } from '@/stores/useAuthStore'
 import { requiredValidator } from '@core/utils/validators'
 import type { Shift, ShiftStatus } from '@/types/section'
 
@@ -18,16 +19,18 @@ const modelValue = defineModel<boolean>({ required: true })
 
 const router = useRouter()
 const route = useRoute()
+const authStore = useAuthStore()
 
+const orgIdRef = computed(() => authStore.currentOrganisation?.id ?? '')
 const eventIdRef = computed(() => props.eventId)
 const sectionIdRef = computed(() => props.sectionId)
 
 const isEditing = computed(() => !!props.shift)
 const isSubEventRef = computed(() => props.isSubEvent)
 
-const { data: timeSlots } = useTimeSlotList(eventIdRef, { includeParent: isSubEventRef })
-const { mutate: createShift, isPending: isCreating } = useCreateShift(eventIdRef, sectionIdRef)
-const { mutate: updateShift, isPending: isUpdating } = useUpdateShift(eventIdRef, sectionIdRef)
+const { data: timeSlots } = useTimeSlotList(orgIdRef, eventIdRef, { includeParent: isSubEventRef })
+const { mutate: createShift, isPending: isCreating } = useCreateShift(orgIdRef, eventIdRef, sectionIdRef)
+const { mutate: updateShift, isPending: isUpdating } = useUpdateShift(orgIdRef, eventIdRef, sectionIdRef)
 
 const isPending = computed(() => isCreating.value || isUpdating.value)