feat(log): decouple log storage from ClickHouse with switchable logstore

- New internal/repository/logstore abstraction: exported domain interfaces
  (AccessLogStore/ObservabilityStore/UserAccessLogStore/StatusStore),
  config-driven provider (Active/Build/Migrating/SetConfigReader), GORM
  implementation for PostgreSQL/SQLite (incl. hourly rollups computed in
  real time, migration listers, PG partition maintenance), and a ClickHouse
  wrapper preserving the native batch path; repository facade delegates to
  logstore; import-lint test enforces apps never import analyticsrepo.
- ClickHouse is now optional: the log DB is either the main DB (postgres
  when database.enabled, else sqlite) or clickhouse; boot validation +
  first-run seed; log_database / log_db_migration are protected keys.
- New user task 切换日志数据库 (of_log_db_switch): freeze log writes,
  drain batch writers, copy all 6 raw log tables by id (preserving IDs)
  with target-partition pre-creation for PG, flip log_database on success,
  clear the freeze flag on failure.
- Per-store retention (log_retention_days_*) with expiry cleanup folded
  into the daily system_cleanup task; legacy database_auto_cleanup_* and
  of_database_auto_cleanup decommissioned.
- goose migrations: 6 log tables in PG (2 monthly-partitioned) + SQLite,
  retention config seeds, schedule cleanup; GET
  /api/v1/admin/status/log-database endpoint; frontend retention settings,
  switch-task UI and status badge; changelog and docs updated.

docs(plan): log database decoupling implementation plan

docs(design): log database decoupling design (ClickHouse optional)

internal/apps/upload/task/cleanup.go

@@ -18,6 +18,7 @@ import (
 	"github.com/Rain-kl/Wavelet/internal/infra/task"
 	"github.com/Rain-kl/Wavelet/internal/model"
 	"github.com/Rain-kl/Wavelet/internal/repository"
+	"github.com/Rain-kl/Wavelet/internal/repository/logstore"
 	"github.com/Rain-kl/Wavelet/pkg/logger"
 )
 
@@ -129,6 +130,17 @@ func (h *SystemCleanupHandler) Execute(ctx context.Context, _ []byte) (*task.Tas
 		)
 	}
 
+	task.AppendLog(ctx, "开始清理过期日志（按当前日志库保留天数）...")
+	summary, err := logstore.CleanupExpired(ctx)
+	switch {
+	case err != nil:
+		task.AppendLog(ctx, "清理过期日志失败: %v", err)
+	case summary.Deleted == 0:
+		task.AppendLog(ctx, "没有需要清理的过期日志 (保留 %d 天)", summary.RetentionDays)
+	default:
+		task.AppendLog(ctx, "日志清理完成：保留 %d 天，删除 %d 条", summary.RetentionDays, summary.Deleted)
+	}
+
 	msg := fmt.Sprintf("系统清理完成。成功清理未使用的上传文件 %d/%d 个；清理历史推送审计日志 %d 条；清理任务执行日志 %d 条。",
 		totalDeleted,
 		totalProcessed,