feat(system): page Status avec endpoint API Platform et composants Vue

- Nouveau domaine System/Domain/Model/SystemStatus (value object)
- QueryHandler agrégeant métriques mangas, chapitres, jobs (global/24h/7j), stockage et sources
- Endpoint GET /api/system/status via API Platform (singleton)
- Calcul de l'espace disque par RecursiveDirectoryIterator sur public/images
- Page Vue /system/status avec 6 cards (Mangas, Chapitres, Jobs, Stockage, Sources, Système)
- Nettoyage du router : suppression des PlaceholderComponent et routes placeholder
- Sidebar : suppression des entrées sans page réelle

assets/vue/app/domain/system/presentation/components/JobsStatusCard.vue

@@ -0,0 +1,104 @@
+<template>
+    <StatusCard title="Jobs" :icon="CpuChipIcon">
+        <!-- Onglets -->
+        <div class="flex gap-1 mb-3 border-b border-gray-200 dark:border-gray-700">
+            <button
+                v-for="tab in tabs"
+                :key="tab.key"
+                @click="activeTab = tab.key"
+                class="px-3 py-1.5 text-xs font-medium transition-colors"
+                :class="activeTab === tab.key
+                    ? 'border-b-2 border-blue-500 text-blue-600 dark:text-blue-400'
+                    : 'text-gray-500 hover:text-gray-700 dark:hover:text-gray-300'">
+                {{ tab.label }}
+            </button>
+        </div>
+
+        <!-- Contenu -->
+        <template v-if="activeTab === 'global'">
+            <div class="grid grid-cols-2 gap-2">
+                <Metric label="Total" :value="status.totalJobs" />
+                <Metric label="En cours" :value="status.inProgressJobs" color="blue" />
+                <Metric label="Terminés" :value="status.completedJobs" color="green" />
+                <Metric label="En attente" :value="status.pendingJobs" color="yellow" />
+                <Metric label="Échoués" :value="status.failedJobs" color="red" />
+            </div>
+        </template>
+
+        <template v-else-if="activeTab === '24h'">
+            <div class="grid grid-cols-2 gap-2">
+                <Metric label="Total" :value="status.totalJobsLast24h" />
+                <Metric label="Terminés" :value="status.completedJobsLast24h" color="green" />
+                <Metric label="Échoués" :value="status.failedJobsLast24h" color="red" />
+                <div class="col-span-2">
+                    <p class="text-xs text-gray-500 mb-1">Taux de succès</p>
+                    <span class="text-xl font-bold" :class="rateColor(status.successRateLast24h)">
+                        {{ status.successRateLast24h }}%
+                    </span>
+                </div>
+            </div>
+        </template>
+
+        <template v-else>
+            <div class="grid grid-cols-2 gap-2">
+                <Metric label="Total" :value="status.totalJobsLast7d" />
+                <Metric label="Terminés" :value="status.completedJobsLast7d" color="green" />
+                <Metric label="Échoués" :value="status.failedJobsLast7d" color="red" />
+                <div class="col-span-2">
+                    <p class="text-xs text-gray-500 mb-1">Taux de succès</p>
+                    <span class="text-xl font-bold" :class="rateColor(status.successRateLast7d)">
+                        {{ status.successRateLast7d }}%
+                    </span>
+                </div>
+            </div>
+        </template>
+    </StatusCard>
+</template>
+
+<script setup>
+import { ref } from 'vue';
+import { CpuChipIcon } from '@heroicons/vue/24/outline';
+import StatusCard from './StatusCard.vue';
+
+defineProps({
+    status: {
+        type: Object,
+        required: true,
+    },
+});
+
+const activeTab = ref('global');
+
+const tabs = [
+    { key: 'global', label: 'Global' },
+    { key: '24h', label: '24h' },
+    { key: '7j', label: '7 jours' },
+];
+
+function rateColor(rate) {
+    if (rate >= 80) return 'text-green-600 dark:text-green-400';
+    if (rate >= 50) return 'text-yellow-600 dark:text-yellow-400';
+    return 'text-red-600 dark:text-red-400';
+}
+
+const Metric = {
+    props: {
+        label: String,
+        value: Number,
+        color: { type: String, default: 'gray' },
+    },
+    template: `
+        <div>
+            <p class="text-xs text-gray-500">{{ label }}</p>
+            <p class="text-lg font-semibold"
+               :class="{
+                 'text-gray-900 dark:text-white': color === 'gray',
+                 'text-green-600 dark:text-green-400': color === 'green',
+                 'text-red-600 dark:text-red-400': color === 'red',
+                 'text-yellow-600 dark:text-yellow-400': color === 'yellow',
+                 'text-blue-600 dark:text-blue-400': color === 'blue',
+               }">{{ value }}</p>
+        </div>
+    `,
+};
+</script>