fix(session): validate existing repository before update

[Aditya7880900936]

Summary

• Validate the existing repository's origin before updating a local repo session.
• Prevent Git operations from running against an unrelated repository when repo.dir points to the wrong checkout.
• Normalize common HTTPS and SSH repository URL formats before comparison.
• Add a regression test covering repository mismatch.

Testing

• npm run build ✅
• npx tsx --test test/*.test.ts ✅
• 77 tests passed, 0 failed.

Closes #85