Add winner archive, host image upload and live demo data

Deliver the demo-ready feature set and seed data so the live site can be
presented end to end:

- Winner archive: ArchivedWinner domain, admin CRUD endpoints/view/manager
  and public archive surface, backed by AddArchivedWinners migration.
- Host presentation: host image upload and artist name on SiteSettings with
  public image endpoint and supporting migrations.
- Clip submissions: idempotent table-ensure migration plus current-season
  demo clips for review workflows.
- Demo seed data: sponsors, share links and 2025 archived winners, with a
  guarded RemoveDemoSeasons cleanup; all seeds guard against real data.
- EnsureRuntimeSchemaParity migration to align runtime schema defensively.
- Admin/home UI refinements; remove unused team role permissions modal and
  dead share-quick-links code.

All seed and schema migrations are idempotent (IF NOT EXISTS / ON CONFLICT)
and skip when real season data is present.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/components/admin/AdminSessionTimeoutCard.vue

@@ -39,7 +39,7 @@ defineProps<{
         />
       </label>
       <div class="rounded-2xl border border-violet-100 bg-violet-50/60 px-4 py-3 text-sm leading-6 text-violet-900">
-        Der Logout reagiert auf echte Nutzeraktivitaet wie Klicks, Tasten, Scrollen oder Touch. Die Session bleibt serverseitig trotzdem autoritativ und laeuft spaetestens nach 30 Tagen absolut ab.
+        Der Logout reagiert auf echte Nutzeraktivität wie Klicks, Tasten, Scrollen oder Touch. Die Session bleibt serverseitig trotzdem autoritativ und läuft spätestens nach 30 Tagen absolut ab.
       </div>
     </div>
   </section>