Align backend with frontend, make clips end-to-end, polish admin

Backend
- Add ClipSubmission entity + table (runtime bootstrapper) and
  POST /api/public/clips (server-derives platform from the link)
- Surface clip submissions in the admin season detail
- Add DELETE candidate/category/clip endpoints with audit entries

Frontend
- Clips admin: real moderation view (list, open link, delete) instead
  of placeholder; wired clipSubmissions through types/api/store
- Categories admin: add delete with confirm modal (matches Candidates)
- Voting ranking bar uses the unified purple gradient
- Fix ASCII transliterations to proper German umlauts across admin
- Remove orphan AdminView 2.vue

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

frontend/src/components/admin/AdminSeasonToolbar.vue

@@ -42,7 +42,7 @@ const yearStats = computed(() => [
           <div class="min-w-0">
             <p class="text-xs font-semibold uppercase tracking-[0.24em] text-violet-500">Aktuelles Award-Jahr</p>
             <h2 class="truncate text-xl font-semibold text-slate-900">
-              {{ currentSeason.year || 'Kein Jahr' }} · {{ currentSeason.name || 'Bitte Jahr auswaehlen' }}
+              {{ currentSeason.year || 'Kein Jahr' }} · {{ currentSeason.name || 'Bitte Jahr auswählen' }}
             </h2>
           </div>
         </div>
@@ -54,7 +54,7 @@ const yearStats = computed(() => [
           </span>
           <span class="inline-flex items-center gap-2 rounded-full border px-3 py-1.5 text-xs font-semibold" :class="currentSeason.isCurrent ? 'border-emerald-100 bg-emerald-50 text-emerald-700' : 'border-slate-100 bg-slate-50 text-slate-500'">
             <CheckCircle2 class="h-3.5 w-3.5" />
-            {{ currentSeason.isCurrent ? 'Oeffentlich sichtbar' : 'Nicht oeffentlich' }}
+            {{ currentSeason.isCurrent ? 'Öffentlich sichtbar' : 'Nicht öffentlich' }}
           </span>
         </div>
       </div>