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/drivers/driver_asynq_worker/executor.go

@@ -19,10 +19,10 @@ import (
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/idgen"
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
-	otel_trace "github.com/Rain-kl/Wavelet/backend/pkg/trace"
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/pkg/idgen"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
+	otel_trace "github.com/Rain-kl/Wavelet/pkg/trace"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 )
 
 var (

backend/plugins/drivers/driver_asynq_worker/executor_test.go

@@ -18,7 +18,7 @@ import (
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/testhelper"
+	"github.com/Rain-kl/Wavelet/pkg/testhelper"
 )
 
 // mockHandler 用于测试的模拟任务处理器

backend/plugins/drivers/driver_asynq_worker/plugin.go

@@ -14,7 +14,7 @@ import (
 
 	"github.com/hibiken/asynq"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
+	"github.com/Rain-kl/Wavelet/core"
 )
 
 const (

backend/plugins/drivers/driver_asynq_worker/task_repo.go

@@ -12,9 +12,9 @@ import (
 
 	"github.com/redis/go-redis/v9"
 
-	"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/drivers/driver_asynq_worker/types.go

@@ -10,7 +10,7 @@ import (
 
 	"gorm.io/gorm"
 
-	db "github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	db "github.com/Rain-kl/Wavelet/plugins/infra/database"
 )
 
 // TaskExecutionStatus 任务执行状态

backend/plugins/drivers/driver_asynq_worker/utils.go

@@ -9,7 +9,7 @@ import (
 	"github.com/redis/go-redis/v9"
 	"github.com/redis/go-redis/v9/maintnotifications"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/config"
+	"github.com/Rain-kl/Wavelet/pkg/config"
 )
 
 type redisClientConnOpt struct {

backend/plugins/drivers/driver_asynq_worker/utils_test.go

@@ -6,7 +6,7 @@ package driver_asynq_worker
 import (
 	"testing"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/config"
+	"github.com/Rain-kl/Wavelet/pkg/config"
 	"github.com/redis/go-redis/v9/maintnotifications"
 )