Add SauceLabs build pruning script

[jleach]

Summary

All feature branch builds are now pushed to SauceLabs (SL), causing build accumulation. We need a script to prune stale PR builds once they've been superseded by a release candidate on main.

Background

Our CI (ship-to-saucelabs action) uploads builds to SauceLabs with the following tagging scheme:

• PR builds: tagged pr, pr-<number>
• Main branch builds: tagged rc

Build names include github.run_number (e.g. BCWallet-1234.ipa). Uploads target both iOS and Android across two build types (bc-wallet, single-app), so there are 4 artifacts per CI run.

API endpoint: https://api.us-west-1.saucelabs.com/v1/storage/ (auth via SAUCE_USERNAME + SAUCE_ACCESS_KEY).

Requirements

Pruning Logic

1. Query SauceLabs storage API for all files tagged rc
2. Extract the greatest build number (from the filename, e.g. BCWallet-1234.ipa → 1234)
3. Query all files tagged pr
4. Delete any pr-tagged file whose build number is less than the max rc build number

Script

• Language: Node.js
• Location: scripts/prune-saucelabs/ (with its own package.json)
• Auth: Read SAUCE_USERNAME and SAUCE_ACCESS_KEY from environment variables
• Dry-run by default: The script should default to dry-run mode (list what would be deleted). Require an explicit --execute flag to actually delete.
• Logging: Print a summary of what was found and what was (or would be) deleted
• Platforms: Prune both iOS (.ipa) and Android (.aab) builds

Future Work (out of scope for this issue)

• Add a scheduled GitHub Action to run this script periodically

Acceptance Criteria

• Script lives at scripts/prune-saucelabs/
• Defaults to dry-run; --execute flag performs actual deletion
• Correctly identifies max rc build number and prunes older pr builds
• Handles both iOS and Android artifacts
• Works with SauceLabs v1 storage API
• Logs clearly what it finds and what it deletes (or would delete)