docs(lab2): git internals, reflog recovery, signed tag, and bisect

[fsstilerr]

Goal

Lab 2 submission: Git object model, reflog recovery, signed annotated tag, rebase, and bisect bonus.

Changes

• submissions/lab2.md — write-up for Tasks 1, 2 and the Bonus task
• signed annotated tag v0.1.0-lab2-fsstilerr pushed to the fork

Testing

• Full HEAD -> tree -> blob chain captured with git cat-file
• Two commits destroyed with reset --hard and recovered from reflog
• git tag -v returns Good "git" signature
• git bisect run identified f285ede in 2 tests over a 4-commit range

Checklist

• Title is a clear sentence (<= 70 chars)
• Commits are signed (git log --show-signature)
• submissions/lab2.md updated