refactor: reorganize models to pkg/model and add authentication module

- Move ORM models from internal/model to pkg/model organized by module (auth/k8s/registry)
- Add authentication module with login, user management handlers
- Update all import paths to use new model locations
- Add frontend auth pages (Login, UserManagement) and authStore
- Remove deprecated internal/model/model.go

pkg/model/k8s/config.go

@@ -0,0 +1,18 @@
+package k8s
+
+import (
+	"time"
+
+	"gorm.io/gorm"
+)
+
+// ClusterConfig k8s cluster configuration
+type ClusterConfig struct {
+	ID        uint           `gorm:"primarykey" json:"id"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`
+
+	Key   string `gorm:"uniqueIndex;not null" json:"key"`
+	Value string `gorm:"type:text" json:"value"`
+}