feat(monitoring): T23 - Surveillance automatique des libraries

- Ajout scheduler dans l'indexer (vérifie toutes les minutes)
- Migration 0004: colonnes monitor_enabled, scan_mode, next_scan_at
- API: GET /libraries avec champs monitoring
- API: PATCH /libraries/:id/monitoring pour configuration
- Composant MonitoringForm (client) avec checkbox et select
- Badge Auto/Manual avec couleurs différentes
- Affichage temps restant avant prochain scan
- Proxy route /api/libraries/:id/monitoring

Le scheduler crée automatiquement des jobs quand next_scan_at <= NOW()

apps/backoffice/app/components/MonitoringForm.tsx

@@ -0,0 +1,62 @@
+"use client";
+
+import { useTransition } from "react";
+
+interface MonitoringFormProps {
+  libraryId: string;
+  monitorEnabled: boolean;
+  scanMode: string;
+}
+
+export function MonitoringForm({ libraryId, monitorEnabled, scanMode }: MonitoringFormProps) {
+  const [isPending, startTransition] = useTransition();
+
+  const handleSubmit = (formData: FormData) => {
+    startTransition(async () => {
+      try {
+        const response = await fetch(`/api/libraries/${libraryId}/monitoring`, {
+          method: "PATCH",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({
+            monitor_enabled: formData.get("monitor_enabled") === "true",
+            scan_mode: formData.get("scan_mode"),
+          }),
+        });
+        if (response.ok) {
+          window.location.reload();
+        }
+      } catch (error) {
+        console.error("Failed to update monitoring:", error);
+      }
+    });
+  };
+
+  return (
+    <form action={handleSubmit} className="monitoring-form">
+      <input type="hidden" name="id" value={libraryId} />
+      <label className={`monitor-toggle ${isPending ? 'pending' : ''}`}>
+        <input
+          type="checkbox"
+          name="monitor_enabled"
+          value="true"
+          defaultChecked={monitorEnabled}
+          disabled={isPending}
+        />
+        Auto
+      </label>
+      <select
+        name="scan_mode"
+        defaultValue={scanMode}
+        disabled={isPending}
+      >
+        <option value="manual">Manual only</option>
+        <option value="hourly">Hourly</option>
+        <option value="daily">Daily</option>
+        <option value="weekly">Weekly</option>
+      </select>
+      <button type="submit" className="update-btn" disabled={isPending}>
+        {isPending ? '...' : 'Update'}
+      </button>
+    </form>
+  );
+}