Feature/lab3

[ilnarkhasanov]

Goal

Adds a GitHub Actions CI pipeline with vet, test, and lint jobs that gate merges to main, along with branch protection rules and a lab submission documenting the design decisions.

Changes

• Adds a GitHub Actions CI pipeline (ci.yml) with three parallel jobs: go vet, go test -race, and golangci-lint, triggered on PRs and pushes to main that touch app/ or the workflow itself
• Pins runner (ubuntu-24.04) and all action SHAs to prevent supply-chain attacks like CVE-2025-30066
• Scopes workflow permissions to contents: read (least privilege)
• Configures branch protection rules on main requiring all three checks to pass with no bypass allowed
• Adds a PR template and lab submission with timing analysis, design question answers, and screenshots

Testing

Checked it against lab requirements.

Checklist

• Title is a clear sentence (≤ 70 chars)
• Commits are signed (git log --show-signature)
• submissions/lab3.md updated