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/env.go

@@ -0,0 +1,20 @@
+package helpers
+
+import (
+	"os"
+	"strconv"
+)
+
+func EnvInt(name string, fallback int, minimum int) int {
+	rawValue := os.Getenv(name)
+	if rawValue == "" {
+		return fallback
+	}
+
+	value, err := strconv.Atoi(rawValue)
+	if err != nil || value < minimum {
+		return fallback
+	}
+
+	return value
+}