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.

test.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+cd "$(dirname "$0")"
+
+if [ -n "${GO_BIN:-}" ]; then
+  go_bin="$GO_BIN"
+elif command -v go >/dev/null 2>&1; then
+  go_bin="$(command -v go)"
+elif [ -x /home/linuxbrew/.linuxbrew/bin/go ]; then
+  go_bin=/home/linuxbrew/.linuxbrew/bin/go
+else
+  echo "go not found. Set GO_BIN=/path/to/go or install Go." >&2
+  exit 127
+fi
+
+"$go_bin" test ./... "$@"