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/server/admin.go

@@ -373,6 +373,7 @@ func (app *App) handleAdminSettingsPost(ctx *gin.Context) {
 			return
 		}
 	}
+	applyBoxstoreRuntimeConfig(app.config)
 	ctx.Redirect(http.StatusSeeOther, "/admin/settings")
 }