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/infra/storage/diskcache/cache_test.go

@@ -8,7 +8,7 @@ import (
 	"os"
 	"testing"
 
-	db "github.com/Rain-kl/Wavelet/pkg/persistence"
+	cache "github.com/Rain-kl/Wavelet/plugins/infra/cache"
 	"github.com/Rain-kl/Wavelet/pkg/testhelper"
 )
 
@@ -29,8 +29,8 @@ func TestDiskCacheReloadConfig(t *testing.T) {
 	dbConn.Table("w_system_configs").Where("key = ?", "disk_cache_lru_enabled").Update("value", "false")
 
 	// Invalidate Redis config cache to force DB reload
-	if db.Redis != nil {
-		db.Redis.Del(context.Background(), db.PrefixedKey("system_configs"))
+	if cache.Redis != nil {
+		cache.Redis.Del(context.Background(), cache.PrefixedKey("system_configs"))
 	}
 
 	// Reload config