feat: añade métricas de tareas y cola en /metrics

Co-authored-by: aider (openrouter/openai/gpt-5.1) <aider@aider.chat>

src/http/metrics.ts

@@ -28,6 +28,75 @@ export async function handleMetricsRequest(request: Request, db: Database): Prom
     Metrics.set('allowed_groups_total_blocked', blocked);
   } catch {}
 
+  // Métricas de tareas (gauges derivadas desde BD)
+  try {
+    const row = db
+      .prepare(`
+        SELECT
+          COUNT(*) AS total,
+          SUM(CASE WHEN COALESCE(completed, 0) = 1 THEN 1 ELSE 0 END) AS completed,
+          SUM(CASE WHEN COALESCE(completed, 0) = 0 THEN 1 ELSE 0 END) AS active,
+          SUM(
+            CASE
+              WHEN COALESCE(completed, 0) = 0
+               AND due_date IS NOT NULL
+               AND TRIM(due_date) <> ''
+               AND due_date < strftime('%Y-%m-%d','now')
+            THEN 1 ELSE 0
+            END
+          ) AS overdue
+        FROM tasks;
+      `)
+      .get() as any;
+
+    if (row) {
+      const total = Number(row.total ?? 0);
+      const completed = Number(row.completed ?? 0);
+      const active = Number(row.active ?? 0);
+      const overdue = Number(row.overdue ?? 0);
+
+      Metrics.set('tasks_created_total', total);
+      Metrics.set('tasks_completed_total', completed);
+      Metrics.set('tasks_active', active);
+      Metrics.set('tasks_overdue', overdue);
+    }
+  } catch {}
+
+  // Métricas de cola de respuestas (gauges derivadas desde BD)
+  try {
+    const row = db
+      .prepare(`
+        SELECT
+          COUNT(*) AS pending,
+          MIN(strftime('%s', created_at)) AS oldest_ts,
+          strftime('%s','now') AS now_ts
+        FROM response_queue
+        WHERE status = 'queued';
+      `)
+      .get() as any;
+
+    if (row) {
+      const pending = Number(row.pending ?? 0);
+      Metrics.set('response_queue_pending', pending);
+
+      let ageSeconds = -1;
+      const oldestTs = row.oldest_ts != null ? Number(row.oldest_ts) : null;
+      const nowTs = row.now_ts != null ? Number(row.now_ts) : null;
+
+      if (
+        pending > 0 &&
+        oldestTs != null &&
+        Number.isFinite(oldestTs) &&
+        nowTs != null &&
+        Number.isFinite(nowTs)
+      ) {
+        ageSeconds = Math.max(0, nowTs - oldestTs);
+      }
+
+      Metrics.set('response_queue_oldest_age_seconds', ageSeconds);
+    }
+  } catch {}
+
   // Exponer métrica con el tiempo restante hasta el próximo group sync (o -1 si scheduler inactivo)
   try {
     const secs = GroupSyncService.getSecondsUntilNextGroupSync();