feat(fc2a): add SettingsView shell with Overview tab (SystemStatsCards)

Overview tab shows total images/tags/storage/pending/failed using
Fraunces for the big numbers. Inline alert nudges the operator to the
Import tab when pending tasks exist. Polls /api/system/stats every 5s
while the tab is visible (pauses when the document is hidden).

Import tab references three placeholders (TriggerPanel/FiltersForm/
TaskList); real implementations land in Task 15.

Router replaces the placeholder view for /settings with SettingsView.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/settings/ImportFiltersForm.vue

@@ -0,0 +1 @@
+<template><div class="text-caption">ImportFiltersForm — implemented in Task 15</div></template>

frontend/src/components/settings/ImportTaskList.vue

@@ -0,0 +1 @@
+<template><div class="text-caption">ImportTaskList — implemented in Task 15</div></template>

frontend/src/components/settings/ImportTriggerPanel.vue

@@ -0,0 +1 @@
+<template><div class="text-caption">ImportTriggerPanel — implemented in Task 15</div></template>

frontend/src/components/settings/SystemStatsCards.vue

@@ -0,0 +1,63 @@
+<template>
+  <v-row dense>
+    <v-col v-for="card in cards" :key="card.label" cols="12" sm="6" md="4" lg="2">
+      <v-card class="fc-stat">
+        <v-card-text>
+          <div class="fc-stat__label text-caption">{{ card.label }}</div>
+          <div class="fc-stat__value">{{ card.value }}</div>
+        </v-card-text>
+      </v-card>
+    </v-col>
+  </v-row>
+</template>
+
+<script setup>
+import { computed } from 'vue'
+
+const props = defineProps({
+  stats: { type: Object, default: null }
+})
+
+function formatBytes(bytes) {
+  if (!bytes) return '0 B'
+  const units = ['B', 'KiB', 'MiB', 'GiB', 'TiB']
+  let i = 0
+  let value = bytes
+  while (value >= 1024 && i < units.length - 1) { value /= 1024; i++ }
+  return `${value.toFixed(value >= 100 || i === 0 ? 0 : 1)} ${units[i]}`
+}
+
+const cards = computed(() => {
+  const s = props.stats
+  if (!s) return [
+    { label: 'Total images', value: '—' },
+    { label: 'Total tags', value: '—' },
+    { label: 'Storage used', value: '—' },
+    { label: 'Pending tasks', value: '—' },
+    { label: 'Failed tasks', value: '—' }
+  ]
+  return [
+    { label: 'Total images', value: s.total_images.toLocaleString() },
+    { label: 'Total tags',   value: s.total_tags.toLocaleString() },
+    { label: 'Storage used', value: formatBytes(s.storage_bytes) },
+    { label: 'Pending',      value: (s.tasks.pending + s.tasks.queued).toLocaleString() },
+    { label: 'Failed',       value: s.tasks.failed.toLocaleString() }
+  ]
+})
+</script>
+
+<style scoped>
+.fc-stat__label {
+  color: rgb(var(--v-theme-on-surface-variant, var(--v-theme-on-surface)));
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+  font-weight: 500;
+}
+.fc-stat__value {
+  font-family: 'Fraunces', Georgia, serif;
+  font-size: 28px;
+  font-weight: 500;
+  color: rgb(var(--v-theme-on-surface));
+  margin-top: 4px;
+}
+</style>

frontend/src/router.js

@@ -1,12 +1,13 @@
 import { createRouter, createWebHistory } from 'vue-router'
 import PlaceholderView from './views/PlaceholderView.vue'
+import SettingsView from './views/SettingsView.vue'
 
 const routes = [
   // FC-2: image backbone
   { path: '/',          name: 'gallery',       component: PlaceholderView, meta: { title: 'Gallery'      } },
   { path: '/showcase',  name: 'showcase',      component: PlaceholderView, meta: { title: 'Showcase'     } },
   { path: '/tags',      name: 'tags',          component: PlaceholderView, meta: { title: 'Tags'         } },
-  { path: '/settings',  name: 'settings',      component: PlaceholderView, meta: { title: 'Settings'     } },
+  { path: '/settings',  name: 'settings',      component: SettingsView,    meta: { title: 'Settings'     } },
 
   // FC-3: subscription backbone
   { path: '/subscriptions', name: 'subscriptions', component: PlaceholderView, meta: { title: 'Subscriptions' } },

frontend/src/views/SettingsView.vue

@@ -0,0 +1,86 @@
+<template>
+  <v-container class="py-6">
+    <h1 class="fc-h1 mb-6">Settings</h1>
+
+    <v-tabs v-model="tab" color="accent" class="mb-4">
+      <v-tab value="overview">Overview</v-tab>
+      <v-tab value="import">Import</v-tab>
+    </v-tabs>
+
+    <v-window v-model="tab">
+      <v-window-item value="overview">
+        <SystemStatsCards :stats="system.stats" />
+        <v-alert
+          v-if="system.stats && (system.stats.tasks.pending + system.stats.tasks.queued) > 0"
+          type="info" variant="tonal" class="mt-4" closable
+        >
+          {{ system.stats.tasks.pending + system.stats.tasks.queued }} import task(s) pending.
+          <v-btn variant="text" size="small" @click="tab = 'import'">Go to Import tab</v-btn>
+        </v-alert>
+      </v-window-item>
+
+      <v-window-item value="import">
+        <ImportTriggerPanel />
+        <v-divider class="my-6" />
+        <ImportFiltersForm />
+        <v-divider class="my-6" />
+        <ImportTaskList />
+      </v-window-item>
+    </v-window>
+  </v-container>
+</template>
+
+<script setup>
+import { onMounted, onUnmounted, ref, watch } from 'vue'
+import { useSystemStore } from '../stores/system.js'
+import { useImportStore } from '../stores/import.js'
+import SystemStatsCards from '../components/settings/SystemStatsCards.vue'
+import ImportTriggerPanel from '../components/settings/ImportTriggerPanel.vue'
+import ImportFiltersForm from '../components/settings/ImportFiltersForm.vue'
+import ImportTaskList from '../components/settings/ImportTaskList.vue'
+
+const tab = ref('overview')
+const system = useSystemStore()
+const importStore = useImportStore()
+
+let pollId = null
+
+function startPolling() {
+  if (pollId) return
+  system.refreshStats()
+  pollId = setInterval(() => {
+    if (!document.hidden) {
+      system.refreshStats()
+      if (tab.value === 'import') importStore.refreshStatus()
+    }
+  }, 5000)
+}
+
+function stopPolling() {
+  if (pollId) { clearInterval(pollId); pollId = null }
+}
+
+onMounted(() => {
+  startPolling()
+  importStore.loadSettings()
+  importStore.refreshStatus()
+  importStore.loadTasks(true)
+})
+onUnmounted(stopPolling)
+
+watch(tab, (t) => {
+  if (t === 'import') {
+    importStore.refreshStatus()
+    importStore.loadTasks(true)
+  }
+})
+</script>
+
+<style scoped>
+.fc-h1 {
+  font-family: 'Fraunces', Georgia, serif;
+  font-size: 32px;
+  font-weight: 500;
+  color: rgb(var(--v-theme-on-surface));
+}
+</style>