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/infra/cache/plugin.go

@@ -11,10 +11,10 @@ import (
 	"sync"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/pkg/cache/ram"
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/pkg/cache/ram"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 	"github.com/redis/go-redis/v9"
 )
 

backend/plugins/infra/cache/plugin_test.go

@@ -13,9 +13,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/cache"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/plugins/infra/cache"
 )
 
 func TestCachePluginOperations(t *testing.T) {

backend/plugins/infra/cache/redis.go

@@ -12,7 +12,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/config"
+	"github.com/Rain-kl/Wavelet/pkg/config"
 	"github.com/redis/go-redis/extra/redisotel/v9"
 	"github.com/redis/go-redis/v9"
 	"github.com/redis/go-redis/v9/maintnotifications"

backend/plugins/infra/database/clickhouse.go

@@ -16,7 +16,7 @@ import (
 
 	"github.com/ClickHouse/clickhouse-go/v2"
 	"github.com/ClickHouse/clickhouse-go/v2/lib/driver"
-	"github.com/Rain-kl/Wavelet/backend/pkg/config"
+	"github.com/Rain-kl/Wavelet/pkg/config"
 	"go.opentelemetry.io/otel/attribute"
 	clickhouseDriver "gorm.io/driver/clickhouse"
 	"gorm.io/gorm"

backend/plugins/infra/database/plugin.go

@@ -7,8 +7,8 @@ package database
 import (
 	"context"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
 	"gorm.io/gorm"
 )
 

backend/plugins/infra/database/plugin_test.go

@@ -13,9 +13,9 @@ import (
 	"github.com/stretchr/testify/require"
 	"gorm.io/gorm"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/plugins/infra/database"
 )
 
 type Item struct {

backend/plugins/infra/database/postgres.go

@@ -12,7 +12,7 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/config"
+	"github.com/Rain-kl/Wavelet/pkg/config"
 	"github.com/glebarez/sqlite"
 	"go.opentelemetry.io/otel/attribute"
 	"gorm.io/driver/postgres"

backend/plugins/infra/database/postgres_logger.go

@@ -11,7 +11,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
 	"gorm.io/gorm"
 	gormLogger "gorm.io/gorm/logger"
 )

backend/plugins/infra/infra_test.go

@@ -19,13 +19,13 @@ import (
 	"github.com/stretchr/testify/require"
 	"gorm.io/gorm"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/cache"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/logger"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/storage"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/storage/objectstore"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/plugins/infra/cache"
+	"github.com/Rain-kl/Wavelet/plugins/infra/database"
+	"github.com/Rain-kl/Wavelet/plugins/infra/logger"
+	"github.com/Rain-kl/Wavelet/plugins/infra/storage"
+	"github.com/Rain-kl/Wavelet/plugins/infra/storage/objectstore"
 )
 
 type TestUser struct {

backend/plugins/infra/logger/plugin.go

@@ -9,9 +9,9 @@ import (
 	"fmt"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/pkg/logger"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/pkg/logger"
 )
 
 // Plugin implements core.Plugin to provide contracts.LoggerService.

backend/plugins/infra/logger/plugin_test.go

@@ -10,9 +10,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/logger"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/plugins/infra/logger"
 )
 
 func TestLoggerPluginOperations(t *testing.T) {

backend/plugins/infra/storage/diskcache/cache.go

@@ -10,8 +10,8 @@ import (
 	"sync"
 	"time"
 
-	pkgcache "github.com/Rain-kl/Wavelet/backend/pkg/cache/disk"
-	database "github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	pkgcache "github.com/Rain-kl/Wavelet/pkg/cache/disk"
+	database "github.com/Rain-kl/Wavelet/plugins/infra/database"
 )
 
 // Status represents the runtime cache statistics.

backend/plugins/infra/storage/diskcache/cache_test.go

@@ -8,8 +8,8 @@ import (
 	"os"
 	"testing"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/testhelper"
-	cache "github.com/Rain-kl/Wavelet/backend/plugins/infra/cache"
+	"github.com/Rain-kl/Wavelet/pkg/testhelper"
+	cache "github.com/Rain-kl/Wavelet/plugins/infra/cache"
 )
 
 func TestDiskCacheReloadConfig(t *testing.T) {

backend/plugins/infra/storage/objectstore/config.go

@@ -12,7 +12,7 @@ import (
 	"strings"
 	"time"
 
-	database "github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	database "github.com/Rain-kl/Wavelet/plugins/infra/database"
 
 	"gorm.io/gorm"
 )

backend/plugins/infra/storage/objectstore/http.go

@@ -10,7 +10,7 @@ import (
 	"net/url"
 	"time"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/httppool"
+	"github.com/Rain-kl/Wavelet/pkg/httppool"
 )
 
 func getHTTPObject(ctx context.Context, baseURL, key string) (*Object, error) {

backend/plugins/infra/storage/objectstore/storage.go

@@ -13,10 +13,10 @@ import (
 	"sync"
 	"time"
 
-	cache "github.com/Rain-kl/Wavelet/backend/plugins/infra/cache"
-	database "github.com/Rain-kl/Wavelet/backend/plugins/infra/database"
+	cache "github.com/Rain-kl/Wavelet/plugins/infra/cache"
+	database "github.com/Rain-kl/Wavelet/plugins/infra/database"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/util"
+	"github.com/Rain-kl/Wavelet/pkg/util"
 	"gorm.io/gorm"
 )
 

backend/plugins/infra/storage/objectstore/storage_test.go

@@ -11,7 +11,7 @@ import (
 	"testing"
 	"time"
 
-	cache "github.com/Rain-kl/Wavelet/backend/plugins/infra/cache"
+	cache "github.com/Rain-kl/Wavelet/plugins/infra/cache"
 	"github.com/alicebob/miniredis/v2"
 	"github.com/redis/go-redis/v9"
 )

backend/plugins/infra/storage/objectstore/webdav.go

@@ -11,7 +11,7 @@ import (
 	"path"
 	"strings"
 
-	"github.com/Rain-kl/Wavelet/backend/pkg/httppool"
+	"github.com/Rain-kl/Wavelet/pkg/httppool"
 	"github.com/studio-b12/gowebdav"
 )
 

backend/plugins/infra/storage/plugin.go

@@ -9,11 +9,11 @@ import (
 	"fmt"
 	"io"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/plugins/domain/upload/ingest"
-	uploadmodels "github.com/Rain-kl/Wavelet/backend/plugins/domain/upload/models"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/storage/objectstore"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/plugins/domain/upload/ingest"
+	uploadmodels "github.com/Rain-kl/Wavelet/plugins/domain/upload/models"
+	"github.com/Rain-kl/Wavelet/plugins/infra/storage/objectstore"
 )
 
 // Option configures the storage plugin.

backend/plugins/infra/storage/plugin_test.go

@@ -14,10 +14,10 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
-	"github.com/Rain-kl/Wavelet/backend/core"
-	"github.com/Rain-kl/Wavelet/backend/core/contracts"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/storage"
-	"github.com/Rain-kl/Wavelet/backend/plugins/infra/storage/objectstore"
+	"github.com/Rain-kl/Wavelet/core"
+	"github.com/Rain-kl/Wavelet/core/contracts"
+	"github.com/Rain-kl/Wavelet/plugins/infra/storage"
+	"github.com/Rain-kl/Wavelet/plugins/infra/storage/objectstore"
 )
 
 type mockStorageBackend struct {