docs(lab2): version control deep dive submission

[HNS2112]

Goal

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

Changes

• submissions/lab2.md — report covering Tasks 1–2 and the bonus
• evidence/lab2/ — raw command outputs

Testing

Plumbing chain traversed (HEAD → tree → blob → file). Two commits destroyed with reset --hard and recovered via reflog.
Tag v0.1.0-lab2-HNS2112 verified with git tag -v — Good signature. Branch rebased onto moved main; both commits re-signed.
Bisect identified f285ede as the first bad commit (>= → > off-by-one in store.load()).

Checklist

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