fix(download-archive): correctly parse deployment id

[erebe]

Summary by cubic

Fixes execution ID parsing in download-s3-archive so IDs carrying both a deployment id and a Unix timestamp are handled correctly.

• Previously a timestamp was only stripped from a bare UUID; IDs like <uuid>-<id>-<timestamp> were rejected or truncated incorrectly.
• The new parser strips only a trailing 10-digit timestamp and keeps shorter numeric suffixes as part of the key.
• Adds a test suite covering valid and invalid ID shapes.

^{Written for commit 7914f8b. Summary will update on new commits.}

[cubic-dev-ai]

All reported issues were addressed across 2 files

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