fix(audit): H2 audit-view dedupe, M3/M4 honest labels, M10 documenso DLQ alert

H2: audit-page view audit row was firing on every filter change. Now
deduped per-user via Redis SET NX with a 60s TTL, so heavy filter-
tweaking writes one self-reference per minute instead of dozens.

R2-M3: /admin landing card for Onboarding said "Initial-setup wizard
for fresh ports" — the page is a static checklist that even calls
itself "what this page will become". Relabelled to "Onboarding
checklist · Setup checklist for fresh ports (read-only references)."

R2-M4: same for Backup & Restore — landing card promised "on-demand
exports" while the page renders only docs. Relabelled to "Backup
posture + retention policy (read-only)."

R2-M10: documenso-void worker had no DLQ alert hook — a persistent
401/403 from Documenso retried until BullMQ exhausted attempts and
the failure disappeared into audit. Now on final-attempt failure
we notify all super-admins via createNotification with a deduplicating
key per documentId, surfacing the 'void manually in Documenso if
still active' actionable.

1175/1175 vitest passing.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/(dashboard)/[portSlug]/admin/page.tsx

@@ -197,7 +197,7 @@ const GROUPS: AdminGroup[] = [
       {
         href: 'backup',
         label: 'Backup & Restore',
-        description: 'Database snapshots and on-demand exports.',
+        description: 'Backup posture + retention policy (read-only).',
         icon: HardDrive,
       },
       {
@@ -221,8 +221,8 @@ const GROUPS: AdminGroup[] = [
       },
       {
         href: 'onboarding',
-        label: 'Onboarding',
-        description: 'Initial-setup wizard for fresh ports.',
+        label: 'Onboarding checklist',
+        description: 'Setup checklist for fresh ports (read-only references).',
         icon: LayoutDashboard,
       },
     ],