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/infra/persistence/migrator/migrator_test.go

@@ -21,8 +21,10 @@ import (
 
 // expectedMigratedSystemConfigCount 包含初始 32 项系统配置、202606220004
 // 从 of_options 迁移过来的 48 项业务配置、Pages 的 2 项业务配置、
-// OpenResty 默认限流的 3 项业务配置，以及单 IP 请求频率限制 1 项业务配置。
-const expectedMigratedSystemConfigCount = 86
+// OpenResty 默认限流的 3 项业务配置、单 IP 请求频率限制 1 项业务配置、
+// 源站错误页选项 4 项（202608060001 的 3 项 + 202608060002 的 1 项），
+// 以及 202608080002 新增 3 项日志保留天数业务配置并删除 2 项旧清理配置（净 +1）。
+const expectedMigratedSystemConfigCount = 91
 
 func TestMigrateInitializesSQLiteDatabase(t *testing.T) {
 	sqliteDB, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{