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/openflare/async_tasks_test.go

@@ -6,7 +6,6 @@ package openflare
 import (
 	"context"
 	"testing"
-	"time"
 
 	db "github.com/Rain-kl/Wavelet/internal/infra/persistence"
 	"github.com/Rain-kl/Wavelet/internal/model"
@@ -17,63 +16,6 @@ import (
 	"gorm.io/gorm"
 )
 
-func TestDatabaseAutoCleanupHandlerSkipsWhenDisabled(t *testing.T) {
-	sqliteDB, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
-		DisableForeignKeyConstraintWhenMigrating: true,
-	})
-	require.NoError(t, err)
-	require.NoError(t, sqliteDB.AutoMigrate(&model.SystemConfig{}))
-	db.SetDB(sqliteDB)
-	t.Cleanup(func() { db.SetDB(nil) })
-
-	ctx := context.Background()
-	require.NoError(t, repository.SaveOrUpdateSystemConfig(ctx, model.ConfigKeyDatabaseAutoCleanupEnabled, "false"))
-
-	result, err := (&DatabaseAutoCleanupHandler{}).Execute(ctx, nil)
-	require.NoError(t, err)
-	require.NotNil(t, result)
-	assert.Contains(t, result.Message, "未启用")
-}
-
-func TestDatabaseAutoCleanupHandlerDeletesRowsWhenEnabled(t *testing.T) {
-	sqliteDB, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
-		DisableForeignKeyConstraintWhenMigrating: true,
-	})
-	require.NoError(t, err)
-	require.NoError(t, sqliteDB.AutoMigrate(&model.SystemConfig{}))
-	db.SetDB(sqliteDB)
-	resetAccessLogStore := repository.SetAccessLogStoreForTest(repository.NewMemoryAccessLogStore())
-	resetObservabilityStore := repository.SetObservabilityStoreForTest(repository.NewMemoryObservabilityStore())
-	t.Cleanup(func() {
-		resetObservabilityStore()
-		resetAccessLogStore()
-		db.SetDB(nil)
-	})
-
-	ctx := context.Background()
-	now := time.Now().UTC()
-	require.NoError(t, repository.InsertOpenFlareAccessLogsBatch(ctx, []*model.OpenFlareAccessLog{{
-		NodeID:     "node-a",
-		LoggedAt:   now.Add(-95 * 24 * time.Hour),
-		RemoteAddr: "203.0.113.10",
-		Host:       "example.com",
-		Path:       "/access",
-		StatusCode: 200,
-	}}))
-
-	require.NoError(t, repository.SaveOrUpdateSystemConfig(ctx, model.ConfigKeyDatabaseAutoCleanupEnabled, "true"))
-	require.NoError(t, repository.SaveOrUpdateSystemConfig(ctx, model.ConfigKeyDatabaseAutoCleanupRetentionDays, "1"))
-
-	result, err := (&DatabaseAutoCleanupHandler{}).Execute(ctx, nil)
-	require.NoError(t, err)
-	require.NotNil(t, result)
-	assert.Contains(t, result.Message, "共删除")
-
-	rows, err := repository.ListOpenFlareAccessLogs(ctx, model.OpenFlareAccessLogQuery{Page: 0, PageSize: 10})
-	require.NoError(t, err)
-	assert.Empty(t, rows)
-}
-
 func TestUptimeKumaSyncHandlerSkipsWhenDisabled(t *testing.T) {
 	sqliteDB, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
 		DisableForeignKeyConstraintWhenMigrating: true,