Add db support for workspaces

backend/internal/models/workspace.go

@@ -0,0 +1,16 @@
+package models
+
+import (
+	"time"
+)
+
+type Workspace struct {
+	ID        int       `json:"id" validate:"required,min=1"`
+	UserID    int       `json:"userId" validate:"required,min=1"`
+	Name      string    `json:"name" validate:"required"`
+	CreatedAt time.Time `json:"createdAt"`
+}
+
+func (w *Workspace) Validate() error {
+	return validate.Struct(w)
+}