refactor(server): use boxstore helpers and file status consts

- Move box ID validation, file listing/pathing, manifest creation, and uploads to `boxstore`
- Use shared helpers for safe filenames and polling interval env parsing
- Add file status constants to `models` to avoid duplicated magic strings across handlersrefactor(server): use boxstore helpers and file status consts

- Move box ID validation, file listing/pathing, manifest creation, and uploads to `boxstore`
- Use shared helpers for safe filenames and polling interval env parsing
- Add file status constants to `models` to avoid duplicated magic strings across handlers

lib/helpers/format.go

@@ -0,0 +1,20 @@
+package helpers
+
+import "fmt"
+
+func FormatBytes(bytes int64) string {
+	units := []string{"B", "KB", "MB", "GB"}
+	size := float64(bytes)
+	unitIndex := 0
+
+	for size >= 1024 && unitIndex < len(units)-1 {
+		size /= 1024
+		unitIndex++
+	}
+
+	if unitIndex == 0 {
+		return fmt.Sprintf("%d %s", bytes, units[unitIndex])
+	}
+
+	return fmt.Sprintf("%.1f %s", size, units[unitIndex])
+}