feat: impl upload api endpoints

apps/backend/internal/upload/upload.go

@@ -0,0 +1,18 @@
+package upload
+
+import "github.com/get-drexa/drexa/internal/virtualfs"
+
+type Status string
+
+const (
+	StatusPending   Status = "pending"
+	StatusCompleted Status = "completed"
+	StatusFailed    Status = "failed"
+)
+
+type Upload struct {
+	ID         string          `json:"id"`
+	Status     Status          `json:"status"`
+	TargetNode *virtualfs.Node `json:"-"`
+	UploadURL  string          `json:"uploadUrl"`
+}