refactor(structure): group platform, infra, and shared packages

Move process wiring, technical adapters, and cross-cutting contracts out of flat internal/ packages so new code has a clear home without changing business layout.

internal/apps/admin/user/logics.go

@@ -10,8 +10,8 @@ import (
 	"time"
 
 	"github.com/Rain-kl/Wavelet/internal/apps/oauth"
-	"github.com/Rain-kl/Wavelet/internal/db"
-	"github.com/Rain-kl/Wavelet/internal/db/idgen"
+	"github.com/Rain-kl/Wavelet/internal/infra/persistence"
+	"github.com/Rain-kl/Wavelet/internal/infra/persistence/idgen"
 	"github.com/Rain-kl/Wavelet/internal/model"
 	"github.com/Rain-kl/Wavelet/internal/repository"
 )

internal/apps/admin/user/routers.go

@@ -16,7 +16,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"gorm.io/gorm"
 
-	"github.com/Rain-kl/Wavelet/internal/common/response"
+	"github.com/Rain-kl/Wavelet/internal/shared/response"
 )
 
 // minPasswordLength 密码最小长度

internal/apps/admin/user/routers_test.go

@@ -17,7 +17,7 @@ import (
 	"github.com/Rain-kl/Wavelet/internal/testhelper"
 	"github.com/gin-gonic/gin"
 
-	"github.com/Rain-kl/Wavelet/internal/common/response"
+	"github.com/Rain-kl/Wavelet/internal/shared/response"
 )
 
 func setupTestRouter(authUser *model.User) *gin.Engine {