refactor(msg_gateway): decouple bot gateway and push notification architecture

- Split shared monolithic consts into bot, push, and errs with typed sentinel errors
- Restructure model layer into distinct bot and push subdomains
- Refactor DAO layer to enforce single-owner principle and remove cross-table raw SQL queries
- Decompose 1150+ line service/push.go into push_channel, push_event, push_trigger, push_worker, and push_template
- Clean up controller layer with generic request handlers and parameter validation in controller/base.go
- Streamline plugin.go to core Cordis lifecycle orchestration and remove re-export bloat
- Verify all unit tests, race tests, Cordis architecture rules, and Swagger generation pass cleanly

backend/plugins/domain/msg_gateway/dao/bot_test.go

@@ -0,0 +1,64 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package dao_test
+
+import (
+	"Wavelet/pkg/idgen"
+	"Wavelet/pkg/testhelper"
+	"Wavelet/plugins/domain/msg_gateway/dao"
+	"Wavelet/plugins/domain/msg_gateway/model/entity"
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBotDAO_ChannelAndBinding(t *testing.T) {
+	_ = idgen.Init(1)
+	db, _, cleanup := testhelper.SetupTestEnvironment(t)
+	defer cleanup()
+	require.NoError(t, db.AutoMigrate(&entity.MessageChannel{}, &entity.MessageBinding{}, &entity.MessagePairingCode{}))
+
+	dao.SetDBServiceForTest(stubDBService{db: db})
+	t.Cleanup(func() { dao.SetDBServiceForTest(nil) })
+
+	ctx := context.Background()
+
+	ch := entity.MessageChannel{
+		Name:        "tg_bot",
+		Type:        "telegram",
+		OwnerScope:  "system",
+		Credentials: "encrypted_token",
+		Enabled:     true,
+	}
+	require.NoError(t, dao.CreateMessageChannel(ctx, &ch))
+	assert.NotZero(t, ch.ID)
+
+	code, err := dao.UpsertPairingCode(ctx, ch.ID, "tg_user_1", "ABCD1234", time.Now().Add(10*time.Minute))
+	require.NoError(t, err)
+	assert.Equal(t, "ABCD1234", code.Code)
+
+	// Reusing pairing code
+	code2, err := dao.UpsertPairingCode(ctx, ch.ID, "tg_user_1", "XYZ9999", time.Now().Add(10*time.Minute))
+	require.NoError(t, err)
+	assert.Equal(t, "ABCD1234", code2.Code)
+
+	binding := entity.MessageBinding{
+		UserID:         42,
+		ChannelID:      ch.ID,
+		PlatformUserID: "tg_user_1",
+	}
+	require.NoError(t, dao.CreateMessageBinding(ctx, &binding))
+	assert.NotZero(t, binding.ID)
+
+	bindings, err := dao.ListBindingsByUser(ctx, 42)
+	require.NoError(t, err)
+	assert.Len(t, bindings, 1)
+
+	require.NoError(t, dao.DeleteMessageChannel(ctx, ch.ID))
+	_, err = dao.GetMessageChannel(ctx, ch.ID)
+	assert.Error(t, err)
+}