refactor(members): consolidate Platform Admin + Org members into shared useMembers

- useMembers.ts gains a scope param ('organisation' | 'platform') on list,
  invite, update-role, and remove; endpoints branch accordingly.
- Platform Admin's [id].vue now consumes useMembers via scope='platform';
  deleted the duplicated useInviteOrganisationMember / useRemoveOrganisationMember
  / useUpdateOrganisationMemberRole helpers from useAdmin.ts.
- Deduplicated InviteMemberPayload / UpdateMemberRolePayload / AdminOrganisationMember
  from types/admin.ts; Member is now the canonical type.
- SettingsMembers.vue and EditMemberRoleDialog.vue removed (no remaining imports).
- InviteMemberDialog accepts an optional scope prop and is restricted to the
  two organisation-level roles matching the /members UX.

apps/app/src/components/persons/PersonDetailPanel.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { usePersonDetail, useUpdatePerson } from '@/composables/api/usePersons'
 import { useConfirmMatch, useDismissMatch, useManualLinkPerson, useUnlinkPerson } from '@/composables/api/useIdentityMatches'
-import { useMemberList } from '@/composables/api/useMembers'
+import { useMembersList } from '@/composables/api/useMembers'
 import type { Person, PersonStatus } from '@/types/person'
 import type { Member } from '@/types/member'
 
@@ -31,7 +31,7 @@ const { mutate: manualLink, isPending: isManualLinking } = useManualLinkPerson(o
 const { mutate: unlinkPerson, isPending: isUnlinking } = useUnlinkPerson(orgIdRef, eventIdRef)
 
 // Members for manual link
-const { data: membersResponse } = useMemberList(orgIdRef)
+const { data: membersResponse } = useMembersList('organisation', orgIdRef)
 
 const activeTab = ref('info')