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.

.env.example

@@ -3,6 +3,8 @@ WARPBOX_GUEST_UPLOADS_ENABLED=true
 WARPBOX_API_ENABLED=true
 WARPBOX_ZIP_DOWNLOADS_ENABLED=true
 WARPBOX_ONE_TIME_DOWNLOADS_ENABLED=true
+WARPBOX_ONE_TIME_DOWNLOAD_EXPIRY_SECONDS=604800
+WARPBOX_ONE_TIME_DOWNLOAD_RETRY_ON_FAILURE=false
 
 # Storage and expiry limits (in MB)
 WARPBOX_GLOBAL_MAX_FILE_SIZE_MB=2048
@@ -22,4 +24,4 @@ WARPBOX_DATA_DIR=./data
 
 # Admin Area
 WARPBOX_ADMIN_ENABLED=true
-WARPBOX_ADMIN_PASSWORD=123
+WARPBOX_ADMIN_PASSWORD=123