Redesign public site, add phase gating and clip submission

- Rebuild landing page and Nominations/Voting/Winners views in the
  Jayuhime brand style (purple/gold/pastel-rainbow, stars, PageHero banner)
- Gate participation by season phase (nominate/clip share the nomination
  window, vote in the voting window); hide closed/locked pages from nav
- Add login-gated clip submission flow (link-based) + voting clip links
- Make candidate admin scalable: searchable, filterable, paginated table
  with modal create/edit and confirm-delete; add delete API/store actions
- New reusable Modal and PageHero components, usePhases composable
- Segmented top nav and full-size header on admin routes
- vite: honor PORT env for preview

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

frontend/src/composables/usePhases.ts

@@ -0,0 +1,48 @@
+import { useAwardsStore } from '../stores/awards'
+
+/** Teilnahme-Aktionen und die Phase (Timeline-key), an die sie gekoppelt sind. */
+export type ActionKey = 'nominate' | 'clip' | 'vote'
+
+export const PHASE_KEY: Record<ActionKey, string> = {
+  nominate: 'nomination',
+  clip: 'nomination', // Clips laufen im selben Fenster wie die Nominierung
+  vote: 'voting',
+}
+
+export type PhaseState = 'upcoming' | 'active' | 'done'
+
+export interface PhaseInfo {
+  state: PhaseState
+  open: boolean
+  startLabel: string
+  endLabel: string
+}
+
+function formatDate(date?: string): string {
+  if (!date) return ''
+  const parsed = new Date(`${date}T00:00:00`)
+  return Number.isNaN(parsed.getTime())
+    ? date
+    : parsed.toLocaleDateString('de-DE', { day: '2-digit', month: 'long' })
+}
+
+export function usePhases() {
+  const store = useAwardsStore()
+
+  function infoForPhaseKey(key?: string): PhaseInfo {
+    const item = store.overview.timeline.find((entry) => entry.key === key)
+    const state = (item?.state ?? 'upcoming') as PhaseState
+    return {
+      state,
+      open: state === 'active',
+      startLabel: formatDate(item?.startsAt),
+      endLabel: formatDate(item?.endsAt),
+    }
+  }
+
+  function phaseInfo(action: ActionKey): PhaseInfo {
+    return infoForPhaseKey(PHASE_KEY[action])
+  }
+
+  return { phaseInfo, infoForPhaseKey }
+}