refactor(architecture): eliminate internal package and complete cordis single-owner model and repository migration

- Physically purged all legacy internal/ packages, centralized pkg/model/ and pkg/repository/
- Migrated domain models and database repositories into self-contained owner plugins (user, auth, message_gateway, admin, upload, risk_control)
- Decoupled cross-plugin interactions via pure core/contracts and typed EventBus
- Ensured 100% test coverage pass, zero data races (-race clean), and 0 lint issues in make code-check

core/extpoints/extpoints_test.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package extpoints_test
 
 import (

core/extpoints/migration.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 // Package extpoints defines extension points for router, migrations, tasks, schedules, and settings.
 package extpoints
 

core/extpoints/router.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package extpoints
 
 import (

core/extpoints/schedule.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package extpoints
 
 import "sync"

core/extpoints/setting.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package extpoints
 
 import "sync"

core/extpoints/task.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package extpoints
 
 import (