refactor(layout): relocate go.mod to backend/ and clean import paths to module root

- Relocated go.mod and go.sum into backend/ root directory
- Stripped redundant backend/ segments from all Go imports (github.com/Rain-kl/Wavelet/...)
- Unified Makefile, swagger, and build-test to execute in backend/ module context
- Ensured 100% build-test, code-check, format, and swagger pass

backend/plugins/domain/message_gateway/admin_handlers.go

@@ -7,7 +7,7 @@ import (
 	"net/http"
 	"strconv"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/response"
+	"github.com/Rain-kl/Wavelet/pkg/response"
 	"github.com/gin-gonic/gin"
 )
 

backend/plugins/domain/message_gateway/channels/qq/adapter.go

@@ -11,8 +11,8 @@ import (
 	"sync"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway"
 	"github.com/tencent-connect/botgo"
 	"github.com/tencent-connect/botgo/dto"
 	"github.com/tencent-connect/botgo/event"

backend/plugins/domain/message_gateway/channels/qq/adapter_test.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"testing"
 
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway"
 )
 
 func TestHandleEvent_DropsNonC2C(t *testing.T) {

backend/plugins/domain/message_gateway/channels/telegram/adapter.go

@@ -12,7 +12,7 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway"
 	tele "gopkg.in/telebot.v4"
 )
 

backend/plugins/domain/message_gateway/channels/telegram/adapter_test.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"testing"
 
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway"
 	tele "gopkg.in/telebot.v4"
 )
 

backend/plugins/domain/message_gateway/custom_events_admin_login.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
+	"github.com/Rain-kl/Wavelet/core/contracts"
 )
 
 // AdminLogin is the metadata definition for the admin login event.

backend/plugins/domain/message_gateway/handlers.go

@@ -8,9 +8,9 @@ import (
 	"net/http"
 	"strconv"
 
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/pkg/response"
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/pkg/response"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 	"github.com/gin-gonic/gin"
 )
 

backend/plugins/domain/message_gateway/message_gateway_test.go

@@ -8,8 +8,8 @@ import (
 	"testing"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/testhelper"
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway"
+	"github.com/Rain-kl/Wavelet/pkg/testhelper"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway"
 )
 
 func TestUpsertPairingCode_ReusesUnexpired(t *testing.T) {

backend/plugins/domain/message_gateway/plugin.go

@@ -8,9 +8,9 @@ import (
 	"context"
 	"embed"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/core/extpoints"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/core/extpoints"
 	"github.com/gin-gonic/gin"
 	"github.com/hibiken/asynq"
 )

backend/plugins/domain/message_gateway/plugin_test.go

@@ -11,8 +11,8 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway"
 )
 
 func TestMessageGatewayPluginUnit(t *testing.T) {

backend/plugins/domain/message_gateway/push/custom.go

@@ -13,7 +13,7 @@ import (
 	"net/http"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/httppool"
+	"github.com/Rain-kl/Wavelet/pkg/httppool"
 )
 
 func init() {

backend/plugins/domain/message_gateway/push/email.go

@@ -11,7 +11,7 @@ import (
 	"net/smtp"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 )
 
 func init() {

backend/plugins/domain/message_gateway/push/lark.go

@@ -17,7 +17,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/httppool"
+	"github.com/Rain-kl/Wavelet/pkg/httppool"
 )
 
 func init() {

backend/plugins/domain/message_gateway/push/telegram.go

@@ -12,7 +12,7 @@ import (
 	"net/http"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/httppool"
+	"github.com/Rain-kl/Wavelet/pkg/httppool"
 )
 
 func init() {

backend/plugins/domain/message_gateway/push_channels.go

@@ -11,8 +11,8 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/response"
-	pkgpush "github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway/push"
+	"github.com/Rain-kl/Wavelet/pkg/response"
+	pkgpush "github.com/Rain-kl/Wavelet/plugins/domain/message_gateway/push"
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 )

backend/plugins/domain/message_gateway/push_events.go

@@ -9,11 +9,11 @@ import (
 	"errors"
 	"sync"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
 
-	pkgpush "github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway/push"
+	pkgpush "github.com/Rain-kl/Wavelet/plugins/domain/message_gateway/push"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 	"gorm.io/gorm"
 )
 

backend/plugins/domain/message_gateway/push_handlers.go

@@ -9,9 +9,9 @@ import (
 	"net/http"
 	"strconv"
 
-	pkgpush "github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway/push"
+	pkgpush "github.com/Rain-kl/Wavelet/plugins/domain/message_gateway/push"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/response"
+	"github.com/Rain-kl/Wavelet/pkg/response"
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 )

backend/plugins/domain/message_gateway/push_logics.go

@@ -11,10 +11,10 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	pkgpush "github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway/push"
-	"github.com/Rain-kl/Wavelet/backend/plugins/drivers/driver_asynq_worker"
-	db "github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	pkgpush "github.com/Rain-kl/Wavelet/plugins/domain/message_gateway/push"
+	"github.com/Rain-kl/Wavelet/plugins/drivers/driver_asynq_worker"
+	db "github.com/Rain-kl/Wavelet/plugins/infra/database"
 	"gorm.io/gorm"
 )
 

backend/plugins/domain/message_gateway/push_task_listener.go

@@ -9,8 +9,8 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
-	"github.com/Rain-kl/Wavelet/backend/plugins/drivers/driver_asynq_worker"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
+	"github.com/Rain-kl/Wavelet/plugins/drivers/driver_asynq_worker"
 )
 
 // RegisterTaskListeners subscribes push notification handlers to task completion events.

backend/plugins/domain/message_gateway/push_tasks.go

@@ -9,8 +9,8 @@ import (
 	"errors"
 	"fmt"
 
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/message_gateway/push"
-	"github.com/Rain-kl/Wavelet/backend/plugins/drivers/driver_asynq_worker"
+	"github.com/Rain-kl/Wavelet/plugins/domain/message_gateway/push"
+	"github.com/Rain-kl/Wavelet/plugins/drivers/driver_asynq_worker"
 )
 
 const (

backend/plugins/domain/message_gateway/repository.go

@@ -10,9 +10,9 @@ import (
 
 	"gorm.io/gorm"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/idgen"
-	cachepkg "github.com/Rain-kl/Wavelet/backend/plugins/infra/cache"
-	db "github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	"github.com/Rain-kl/Wavelet/pkg/idgen"
+	cachepkg "github.com/Rain-kl/Wavelet/plugins/infra/cache"
+	db "github.com/Rain-kl/Wavelet/plugins/infra/database"
 )
 
 const (

backend/plugins/domain/message_gateway/runner.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"sync"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
 )
 
 // Runner manages lifecycle for long-lived channel adapters (WebSocket, long-polling, etc.).

backend/plugins/domain/message_gateway/secret.go

@@ -8,8 +8,8 @@ import (
 	"encoding/hex"
 	"encoding/json"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/config"
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/pkg/config"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 )
 
 // CredentialKey is AES-256 hex derived from the session secret.