feat: schedule periodic reports asynchronously

ai_knowledge_base_v2/.env.example

@@ -21,6 +21,13 @@ CONFIG_ENCRYPTION_KEY=replace-with-generated-fernet-key
 BOOTSTRAP_ADMIN_USERNAME=admin
 BOOTSTRAP_ADMIN_PASSWORD=replace-with-strong-password
 BOOTSTRAP_ADMIN_NAME=系统管理员
+PERIODIC_REPORT_WORKER_ENABLED=true
+PERIODIC_REPORT_POLL_SECONDS=5
+PERIODIC_REPORT_STALE_MINUTES=30
+PERIODIC_REPORT_MAX_ATTEMPTS=3
+PERIODIC_REPORT_WEEKLY_ENABLED=true
+PERIODIC_REPORT_MONTHLY_ENABLED=true
+PERIODIC_REPORT_TIMEZONE=Asia/Shanghai
 
 # ============================================
 # 内网穿透（frpc sidecar）