chore(task): run system garbage cleanup once daily

系统定期垃圾清理 cron 由每 2 小时（0 */2 * * *）改为每日凌晨 3 点
（0 3 * * *，Asia/Shanghai），降低非必要高频扫描。新增 PG/SQLite
双方言 goose 迁移（含 Down 回滚）与迁移测试。

docs/changelog/index.md

@@ -28,6 +28,7 @@ sidebar: false
 
 ### 变更
 
+- 系统定期垃圾清理由每 2 小时改为每日执行一次（凌晨 3 点，Asia/Shanghai），降低非必要高频扫描。
 - 服务工作者（SW）注入挑战页改为前台无感知：不再显示「加载中…」文案，页面空白，仅通过浏览器控制台输出 `[sw-challenge]` 调试信息（注册成功/失败/回退重定向），注入过程不打扰访客。
 - 性能指标（CPU/内存/磁盘/网络）与访问日志的保留时长解耦：新增三库共用的 `metric_retention_days` 配置（默认 3 天），系统垃圾清理每日任务按独立短留存清理指标快照；访问日志仍按 `log_retention_days_*` 清理。
 - ClickHouse 改为默认关闭：`clickhouse.enabled` 缺省或为 `false` 时不启用（此前会被强制置为 `true`），日志/指标由 PostgreSQL/SQLite 主库承担；显式 `true` 或设置 `CLICKHOUSE_HOST` / `CLICKHOUSE_ENABLED=true` 时启用。

internal/infra/persistence/migrator/goose/postgres/202608090002_update_system_cleanup_schedule.sql

@@ -0,0 +1,13 @@
+-- +goose Up
+-- 系统定期垃圾清理改为每日执行一次（凌晨 3 点，Asia/Shanghai）。
+-- 此前为每 2 小时（0 */2 * * *）高频扫描，日常清理收益有限，降频减少非必要扫描。
+UPDATE w_schedules
+SET cron = '0 3 * * *',
+    updated_at = CURRENT_TIMESTAMP
+WHERE task_type = 'system_cleanup';
+
+-- +goose Down
+UPDATE w_schedules
+SET cron = '0 */2 * * *',
+    updated_at = CURRENT_TIMESTAMP
+WHERE task_type = 'system_cleanup';

internal/infra/persistence/migrator/goose/sqlite/202608090002_update_system_cleanup_schedule.sql

@@ -0,0 +1,13 @@
+-- +goose Up
+-- 系统定期垃圾清理改为每日执行一次（凌晨 3 点，Asia/Shanghai）。
+-- 此前为每 2 小时（0 */2 * * *）高频扫描，日常清理收益有限，降频减少非必要扫描。
+UPDATE w_schedules
+SET cron = '0 3 * * *',
+    updated_at = CURRENT_TIMESTAMP
+WHERE task_type = 'system_cleanup';
+
+-- +goose Down
+UPDATE w_schedules
+SET cron = '0 */2 * * *',
+    updated_at = CURRENT_TIMESTAMP
+WHERE task_type = 'system_cleanup';

internal/infra/persistence/migrator/system_cleanup_migration_test.go

@@ -0,0 +1,95 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package migrator
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/Rain-kl/Wavelet/internal/model"
+	"github.com/glebarez/sqlite"
+	"github.com/pressly/goose/v3"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+)
+
+const (
+	systemCleanupPreviousMigration = int64(202608090001)
+	systemCleanupMigration         = int64(202608090002)
+	systemCleanupTaskType          = "system_cleanup"
+)
+
+func TestSystemCleanupScheduleMigrationSQLite(t *testing.T) {
+	dbPath := t.TempDir() + "/system-cleanup-migration.db"
+	gormDB, err := gorm.Open(sqlite.Open(dbPath), &gorm.Config{
+		DisableForeignKeyConstraintWhenMigrating: true,
+	})
+	require.NoError(t, err)
+	sqlDB, err := gormDB.DB()
+	require.NoError(t, err)
+	sqlDB.SetMaxOpenConns(1)
+	t.Cleanup(func() { require.NoError(t, sqlDB.Close()) })
+
+	runSystemCleanupScheduleMigration(t, gormDB, sqlDB, dialectSqlite, "goose/sqlite")
+}
+
+func TestSystemCleanupScheduleMigrationPostgres(t *testing.T) {
+	dsn := strings.TrimSpace(os.Getenv("OPENFLARE_TEST_POSTGRES_DSN"))
+	if dsn == "" {
+		t.Skip("OPENFLARE_TEST_POSTGRES_DSN is not set")
+	}
+	gormDB, err := gorm.Open(postgres.Open(dsn), &gorm.Config{
+		DisableForeignKeyConstraintWhenMigrating: true,
+	})
+	require.NoError(t, err)
+	sqlDB, err := gormDB.DB()
+	require.NoError(t, err)
+	sqlDB.SetMaxOpenConns(1)
+
+	schema := fmt.Sprintf("system_cleanup_migration_%d", time.Now().UnixNano())
+	require.Regexp(t, `^[a-z0-9_]+$`, schema)
+	require.NoError(t, gormDB.Exec(`CREATE SCHEMA "`+schema+`"`).Error)
+	require.NoError(t, gormDB.Exec(`SET search_path TO "`+schema+`"`).Error)
+	t.Cleanup(func() {
+		assert.NoError(t, gormDB.Exec("SET search_path TO public").Error)
+		assert.NoError(t, gormDB.Exec(`DROP SCHEMA IF EXISTS "`+schema+`" CASCADE`).Error)
+		assert.NoError(t, sqlDB.Close())
+	})
+
+	runSystemCleanupScheduleMigration(t, gormDB, sqlDB, dialectPostgres, "goose/postgres")
+}
+
+func runSystemCleanupScheduleMigration(
+	t *testing.T,
+	gormDB *gorm.DB,
+	sqlDB *sql.DB,
+	dialect string,
+	dir string,
+) {
+	t.Helper()
+	goose.SetBaseFS(migrationFS)
+	require.NoError(t, goose.SetDialect(dialect))
+	require.NoError(t, goose.UpTo(sqlDB, dir, systemCleanupPreviousMigration))
+
+	assertSystemCleanupCron(t, gormDB, "0 */2 * * *", "迁移前应为每 2 小时")
+
+	require.NoError(t, goose.UpTo(sqlDB, dir, systemCleanupMigration))
+	assertSystemCleanupCron(t, gormDB, "0 3 * * *", "迁移后应为每日凌晨 3 点")
+
+	require.NoError(t, goose.DownTo(sqlDB, dir, systemCleanupPreviousMigration))
+	assertSystemCleanupCron(t, gormDB, "0 */2 * * *", "回滚后恢复每 2 小时")
+}
+
+func assertSystemCleanupCron(t *testing.T, gormDB *gorm.DB, wantCron, msg string) {
+	t.Helper()
+	var schedule model.Schedule
+	require.NoError(t, gormDB.Where("task_type = ?", systemCleanupTaskType).First(&schedule).Error)
+	assert.Equal(t, wantCron, schedule.Cron, msg)
+}