fix(audit): kill fake install cmds + dead demo CTA; production fonts; scoped error boundary; admin bootstrap seed

Full-site fake-data audit findings:
- SetupWizard showed a curl|sh installer (get.corrosionmgmt.com) and a
  'corrosion-agent' binary that don't exist -> real host-agent commands
- 'View live demo' CTA on 5 marketing pages linked to a login, not a
  demo -> honest 'Sign in'
- Google Fonts @import was silently dropped from the production CSS
  bundle (mid-bundle @import) -> <link> tags in index.html; prod was
  shipping system fallback fonts
- App-root ErrorBoundary bricked the entire SPA (incl. marketing) on a
  single failed fetch until manual reload -> resets on route change +
  content-scoped boundary inside DashboardLayout so nav chrome survives
- Status page KPIs showed fake zeros while the fetch failed -> em dash
- Login lacked the forgot-password link (flow already existed end-to-end)
- AdminSeedService: fresh DB had schema but no login possible; seeds
  super-admin + license from ADMIN_* env when users table is empty

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/ErrorBoundary.vue

@@ -1,8 +1,15 @@
 <script setup lang="ts">
-import { ref, onErrorCaptured } from 'vue'
+import { ref, watch, onErrorCaptured } from 'vue'
+import { useRoute } from 'vue-router'
 import Icon from '@/components/ds/core/Icon.vue'
 import Button from '@/components/ds/core/Button.vue'
 
+withDefaults(defineProps<{
+  /** 'screen' fills the viewport (app root); 'content' fills its container (inside layout chrome) */
+  variant?: 'screen' | 'content'
+}>(), { variant: 'screen' })
+
+const route = useRoute()
 const hasError = ref(false)
 const errorMessage = ref('')
 
@@ -13,6 +20,12 @@ onErrorCaptured((err) => {
   return false
 })
 
+// A failed view must not brick navigation — clear the error when the route changes
+watch(() => route.fullPath, () => {
+  hasError.value = false
+  errorMessage.value = ''
+})
+
 function retry() {
   hasError.value = false
   errorMessage.value = ''
@@ -21,7 +34,7 @@ function retry() {
 </script>
 
 <template>
-  <div v-if="hasError" class="eb-screen">
+  <div v-if="hasError" class="eb-screen" :class="{ 'eb-screen--content': variant === 'content' }">
     <div class="eb-card">
       <div class="eb-icon-wrap">
         <Icon name="triangle-alert" :size="24" :stroke-width="1.75" />
@@ -44,6 +57,11 @@ function retry() {
   padding: var(--space-6);
 }
 
+.eb-screen--content {
+  min-height: 60vh;
+  background: transparent;
+}
+
 .eb-card {
   background: var(--surface-base);
   box-shadow: var(--ring-default), var(--shadow-md);