feat(one-time-downloads): add expiry and retry configuration

Introduce new environment variables to control the behavior of one-time download boxes:
- `WARPBOX_ONE_TIME_DOWNLOAD_EXPIRY_SECONDS`: Sets the lifetime of a one-time box after uploads are complete.
- `WARPBOX_ONE_TIME_DOWNLOAD_RETRY_ON_FAILURE`: Determines whether a box remains available if the ZIP creation or transfer fails.

To support these settings, the ZIP delivery process was refactored to use a temporary file. This ensures that a one-time box is only marked as consumed after the file has been successfully transferred to the client, preventing data loss on network interruptions.

Additionally, added a `DecorateFiles` helper in the box store to reduce code duplication.

lib/boxstore/store.go

@@ -75,6 +75,10 @@ func SetOneTimeDownloadExpiry(seconds int64) {
 	oneTimeDownloadExpiry = seconds
 }
 
+func OneTimeDownloadExpiry() int64 {
+	return oneTimeDownloadExpiry
+}
+
 func UploadRoot() string {
 	return uploadRoot
 }
@@ -185,12 +189,7 @@ func BoxSummary(boxID string) (models.BoxSummary, error) {
 
 func ListFiles(boxID string) ([]models.BoxFile, error) {
 	if manifest, err := reconcileManifest(boxID); err == nil && len(manifest.Files) > 0 {
-		files := make([]models.BoxFile, 0, len(manifest.Files))
-		for _, file := range manifest.Files {
-			files = append(files, DecorateFile(boxID, file))
-		}
-
-		return files, nil
+		return DecorateFiles(boxID, manifest.Files), nil
 	}
 
 	return listCompletedFilesFromDisk(boxID)
@@ -513,6 +512,14 @@ func DecorateFile(boxID string, file models.BoxFile) models.BoxFile {
 	return file
 }
 
+func DecorateFiles(boxID string, files []models.BoxFile) []models.BoxFile {
+	decorated := make([]models.BoxFile, 0, len(files))
+	for _, file := range files {
+		decorated = append(decorated, DecorateFile(boxID, file))
+	}
+	return decorated
+}
+
 func IconForMimeType(mimeType string, filename string) string {
 	extension := strings.ToLower(filepath.Ext(filename))
 
@@ -645,15 +652,13 @@ func startRetentionIfTerminalUnlocked(manifest *models.BoxManifest) {
 	}
 
 	seconds := manifest.RetentionSecs
-	if seconds <= 0 {
-		if manifest.OneTimeDownload {
-			seconds = oneTimeDownloadExpiry
-		} else {
-			seconds = normalizeRetentionOption(manifest.RetentionKey).Seconds
-		}
+	if manifest.OneTimeDownload {
+		seconds = oneTimeDownloadExpiry
+	} else if seconds <= 0 {
+		seconds = normalizeRetentionOption(manifest.RetentionKey).Seconds
 	}
 
-	if manifest.OneTimeDownload && seconds <= 0 {
+	if seconds <= 0 {
 		return
 	}
 
@@ -663,8 +668,6 @@ func startRetentionIfTerminalUnlocked(manifest *models.BoxManifest) {
 		}
 	}
 
-	// seconds is already handled above
-
 	// Retention starts after uploads settle so slow or very large uploads do
 	// not expire before users get a real chance to open the box.
 	manifest.ExpiresAt = time.Now().UTC().Add(time.Duration(seconds) * time.Second)