refactor(admin/members): dedupe STATUS_LABELS + reactive row update

Promote inline STATUS_LABELS copies (admin/members/index.vue,
member/account.vue) into app/config/memberStatus.js, matching the
app/config/circles.js pattern. Drive admin/members/[id].vue status
select from the same constant — completes the alignment started in
441a5f5.

Use the softer member-facing copy as canonical: "Paused" / "Closed"
instead of "Suspended" / "Cancelled".

Also fix markSlackInvited's non-reactive Object.assign on a plain
object inside a useFetch array — replace with index-find + element
reassignment so the row UI refreshes without a manual reload.

app/pages/member/account.vue

@@ -315,6 +315,7 @@
 
 <script setup>
 import { CONTRIBUTION_PRESETS, getGuidanceLabel, requiresPayment } from '~/config/contributions';
+import { STATUS_LABELS } from '~/config/memberStatus';
 
 definePageMeta({
   middleware: "auth",
@@ -417,13 +418,6 @@ const circleOptions = [
   },
 ];
 
-const STATUS_LABELS = {
-  active: "Active",
-  pending_payment: "Setting up payment",
-  suspended: "Paused",
-  cancelled: "Closed",
-};
-
 const formatStatus = (s) => STATUS_LABELS[s] || s;
 
 const capitalise = (s) => (s ? s.charAt(0).toUpperCase() + s.slice(1) : s);