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/indexer/src/main.rs

@@ -92,6 +92,18 @@ async fn ready(State(state): State<AppState>) -> Result<Json<serde_json::Value>,
 
 async fn run_worker(state: AppState, interval_seconds: u64) {
     let wait = Duration::from_secs(interval_seconds.max(1));
+    // Start scheduler task for auto-monitoring
+    let scheduler_state = state.clone();
+    let _scheduler_handle = tokio::spawn(async move {
+        let scheduler_wait = Duration::from_secs(60); // Check every minute
+        loop {
+            if let Err(err) = check_and_schedule_auto_scans(&scheduler_state.pool).await {
+                error!("[SCHEDULER] Error: {}", err);
+            }
+            tokio::time::sleep(scheduler_wait).await;
+        }
+    });
+
     loop {
         match claim_next_job(&state.pool).await {
             Ok(Some((job_id, library_id))) => {
@@ -115,6 +127,69 @@ async fn run_worker(state: AppState, interval_seconds: u64) {
     }
 }
 
+async fn check_and_schedule_auto_scans(pool: &sqlx::PgPool) -> anyhow::Result<()> {
+    let libraries = sqlx::query(
+        r#"
+        SELECT id, scan_mode, last_scan_at
+        FROM libraries
+        WHERE monitor_enabled = TRUE
+          AND (
+            next_scan_at IS NULL
+            OR next_scan_at <= NOW()
+          )
+          AND NOT EXISTS (
+            SELECT 1 FROM index_jobs
+            WHERE library_id = libraries.id
+              AND status IN ('pending', 'running')
+          )
+        "#
+    )
+    .fetch_all(pool)
+    .await?;
+
+    for row in libraries {
+        let library_id: Uuid = row.get("id");
+        let scan_mode: String = row.get("scan_mode");
+        
+        info!("[SCHEDULER] Auto-scanning library {} (mode: {})", library_id, scan_mode);
+        
+        let job_id = Uuid::new_v4();
+        let job_type = match scan_mode.as_str() {
+            "full" => "full_rebuild",
+            _ => "rebuild",
+        };
+        
+        sqlx::query(
+            "INSERT INTO index_jobs (id, library_id, type, status) VALUES ($1, $2, $3, 'pending')"
+        )
+        .bind(job_id)
+        .bind(library_id)
+        .bind(job_type)
+        .execute(pool)
+        .await?;
+        
+        // Update next_scan_at
+        let interval_minutes = match scan_mode.as_str() {
+            "hourly" => 60,
+            "daily" => 1440,
+            "weekly" => 10080,
+            _ => 1440, // default daily
+        };
+        
+        sqlx::query(
+            "UPDATE libraries SET last_scan_at = NOW(), next_scan_at = NOW() + INTERVAL '1 minute' * $2 WHERE id = $1"
+        )
+        .bind(library_id)
+        .bind(interval_minutes)
+        .execute(pool)
+        .await?;
+        
+        info!("[SCHEDULER] Created job {} for library {}", job_id, library_id);
+    }
+    
+    Ok(())
+}
+
 async fn claim_next_job(pool: &sqlx::PgPool) -> anyhow::Result<Option<(Uuid, Option<Uuid>)>> {
     let mut tx = pool.begin().await?;
     let row = sqlx::query(