fix(persistence): migrate all pkg/persistence imports to plugins/infra/database and plugins/infra/cache

- Replace db.DB(ctx) with database.DB(ctx) from plugins/infra/database
- Replace db.Redis/db.PrefixedKey/db.GetJSON/db.SetJSON with cachepkg.* from plugins/infra/cache
- Replace pkg/persistence/idgen with pkg/idgen (already exists)
- Replace pkg/persistence/batchwriter with pkg/batchwriter (already exists)
- Replace pkg/persistence/migrator with pkg/migrator (already exists)
- Replace pkg/persistence/logstore with plugins/domain/risk_control/logstore
- Delete defunct pkg/{persistence,cap,message_gateway,push,shared,task}
- Fix vet issues: db alias in domain_test.go, driver_asynq_worker.TaskHandler reference
- Update Makefile architecture guard
- Update docs and skill references
- Update go.mod: gorilla/sessions promotion to direct dependency

plugins/domain/upload/task/storage_migration_task_test.go

@@ -16,7 +16,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/pkg/persistence"
+	cache "github.com/Rain-kl/Wavelet/plugins/infra/cache"
 	"github.com/Rain-kl/Wavelet/pkg/testhelper"
 	"github.com/Rain-kl/Wavelet/plugins/domain/upload/models"
 	"github.com/Rain-kl/Wavelet/plugins/infra/storage/objectstore"
@@ -239,16 +239,16 @@ func TestMigrationHandlerExecuteWithRedisLock(t *testing.T) {
 	})
 	defer rdb.Close()
 
-	oldRedis := db.Redis
-	db.Redis = rdb
+	oldRedis := cache.Redis
+	cache.Redis = rdb
 	defer func() {
-		db.Redis = oldRedis
+		cache.Redis = oldRedis
 	}()
 
 	ctx := context.Background()
 
 	// Acquire lock manually
-	lockKey := db.PrefixedKey("lock:storage:migrate")
+	lockKey := cache.PrefixedKey("lock:storage:migrate")
 	if err := rdb.Set(ctx, lockKey, "locked", time.Hour).Err(); err != nil {
 		t.Fatalf("Failed to set manual lock in Redis: %v", err)
 	}