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/user/plugin_test.go

@@ -15,7 +15,7 @@ import (
 
 	"github.com/Rain-kl/Wavelet/core"
 	"github.com/Rain-kl/Wavelet/core/contracts"
-	db "github.com/Rain-kl/Wavelet/pkg/persistence"
+	database "github.com/Rain-kl/Wavelet/plugins/infra/database"
 	"github.com/Rain-kl/Wavelet/plugins/domain/user"
 )
 
@@ -30,7 +30,7 @@ func setupTestDB(t *testing.T) *gorm.DB {
 		&user.AccessToken{},
 	))
 
-	db.SetDB(testDB)
+	database.SetDB(testDB)
 	return testDB
 }