fix: Resolve TypeScript build errors blocking Docker nginx build

- DashboardView: Add non-null assertion on upcoming[0] (guarded by length check)
- EarlyAccessView: Add missing `computed` import from Vue

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/admin/DashboardView.vue

@@ -27,7 +27,7 @@ const nextWipeDate = computed<string>(() => {
 
   if (upcoming.length === 0) return 'Not Scheduled'
 
-  return upcoming[0].toLocaleDateString('en-US', {
+  return upcoming[0]!.toLocaleDateString('en-US', {
     month: 'short',
     day: 'numeric',
     hour: '2-digit',

frontend/src/views/marketing/EarlyAccessView.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { ref } from 'vue'
+import { ref, computed } from 'vue'
 import { Shield, Users, Star, MessageCircle, Clock, ChevronRight, Check, Zap, Terminal, RefreshCw, LayoutDashboard } from 'lucide-vue-next'
 
 // ---------- Email capture ----------