feat: capture pre-upgrade snapshots

[itzptk]

Summary

• capture pre-upgrade snapshot metadata for single, batch/all, and smart upgrade jobs
• persist snapshot metadata into job history records
• surface snapshot summaries and detail views in the History screen

Verification

• npm run build
• npm run test:all

[itzptk]

Hermet code review

Verdict: no blocking findings. I could not submit a formal approval because GitHub treats the active account as the PR author, so this is posted as a review comment instead.

Verification

• npm run test:all ✅
• npm run build ✅
• GitHub CI test-and-build ✅

Non-blocking follow-ups

• Add focused HistoryViewComponent coverage for snapshot preview/details click behavior.
• Add explicit upgradeOne / upgradeAll failure-path tests proving snapshots are attached to failed events.
• Consider bounding persisted snapshot size for large upgradeAll histories.
• If multi-version fidelity matters, smart-upgrade snapshots currently store a single installed version from the smart plan.

[itzptk]

Review follow-ups addressed

Commit: 9c5fcb4

• Added focused History UI coverage for snapshot preview/details behavior and verified the Details action does not also open output.
• Added explicit failure-path tests for targeted upgrade and upgrade-all snapshots on failed events.
• Capped persisted pre-upgrade snapshot items at 100 and records omitted count via itemsTruncated.
• Preserved all installed versions for smart-upgrade plan items and smart-upgrade snapshots.

Verification:

• npm run test:all ✅
• npm run build ✅
• GitHub CI test-and-build ✅