feat(portal): customer-admin surface on real data + Stripe billing + session resilience

Access & navigation
- Gate partner-mode strictly to partner staff so admins/end-users never inherit
  leftover partner-view state; purge stale session entry on hydrate.
- Role-driven admin entry: useMe.isTenantAdmin, Admin/Personal tiles in the app
  launcher, and an /admin route guard in the global middleware (fail closed).
- Drop the duplicate user identity block from the sidebar footer.

Admin pages on real data
- New tenant-scoped, membership-gated endpoints: GET /tenants/:slug/{audit,users,
  invoices}; useTenant composable resolves the active workspace + subscription.
- Dashboard: real seats, spend (cycle-normalized + minor-units), plan, renewal,
  and recent audit; unbacked sections removed.
- Users & groups: real members; Groups/Invitations/Service accounts shown as
  honest "coming soon".
- Subscription & invoices: real plan hero, invoice history, and billing details.

Stripe payment method (Elements + SetupIntent)
- StripeClient: publishable key + getDefaultCard/createSetupIntent/setDefaultCard.
- CustomerBillingController + BillingService methods (ensure-customer on demand).
- Portal: PaymentMethodModal, useStripeJs (CDN load), proxies; hidePostalCode.

Editable billing details & whitelabel branding
- PATCH /tenants/:slug/billing-info (narrow: company/VAT/country/email).
- TenantBranding schema/service + GET/PUT /tenants/:slug/branding: real product
  name, accent colour, and per-tenant email-template overrides.
- Branding preview + sidebar workspace mark wired to real name/plan/seats/colour
  with YIQ auto-contrast (readableOn util).

Session resilience
- Request offline_access so Authentik issues a refresh token (automaticRefresh).
- Silent refresh + single retry on 401 for writes (useApiFetch, incl. partner
  pages) and reads (useMe.fetchMe) — no redirect, no lost input.
- Modal backdrop closes only on press+release on the backdrop (no more
  drag-select-to-close).

apps/portal/components/partner/CustomerCreateWizard.vue

@@ -7,6 +7,8 @@
 defineProps<{ open: boolean }>()
 const emit = defineEmits<{ close: []; done: [] }>()
 
+const { request } = useApiFetch()
+
 // 5 steps. Branding was dropped because nothing on the backend persists it
 // yet (no Tenant.branding field, no logo upload pipeline) — partners
 // configure branding post-provisioning via /partner/branding once that
@@ -214,7 +216,7 @@ async function submit() {
       // client so the wizard never sends half-filled admin payloads.
       ...(adminName && adminEmail && { adminName, adminEmail }),
     }
-    const res = await $fetch<{
+    const res = await request<{
       tenant: { name: string }
       adminInvite?: AdminCredentials | { error: string }
     }>('/api/partner/tenants', { method: 'POST', body: payload })