Add PR Size Checker That Warns on Large Diffs and Fails on Very Large Diffs

[vjuliaife]

Description:
Large pull requests are harder to review thoroughly and more likely to introduce undetected bugs, yet TariffShield has no guardrail to discourage oversized changes. A PR size checker that warns when a diff exceeds 400 lines and fails CI when it exceeds 1000 lines nudges contributors to split work into reviewable chunks, improving review quality and reducing merge risk.

Acceptance Criteria:

• Create .github/workflows/pr-size.yml that triggers on pull_request (types: opened, synchronize, reopened) and counts the total lines added plus removed using git diff --stat against the PR base SHA
• If the diff is between 400 and 999 lines, post a PR comment via actions/github-script warning "This PR is large (N lines). Consider splitting it into smaller PRs for easier review." and set the step outcome to neutral (do not fail)
• If the diff is 1000 lines or more, post a PR comment explaining the hard limit and fail the workflow step so the size check becomes a blocking status check
• Exclude auto-generated files from the line count: package-lock.json, Cargo.lock, *.snap test snapshots, and any file under dist/ or target/ are excluded via a .prsize-ignore file at the repo root using the same glob format as .gitignore
• The size thresholds (400 warn, 1000 fail) are configurable via workflow env variables PR_SIZE_WARN and PR_SIZE_FAIL so they can be adjusted without editing workflow logic
• If an oversized PR has a large-pr-approved label applied by a maintainer, the size check is bypassed — allowing emergency large changes with explicit sign-off
• Document the PR size policy in CONTRIBUTING.md under "Pull Request Guidelines" with guidance on how to split a large feature into smaller PRs

Relevant Files:

• .github/workflows/pr-size.yml — new PR size check workflow
• .prsize-ignore — glob patterns for files excluded from line count
• CONTRIBUTING.md — contributor guide (add PR size policy section)

[drsteinerdj]

Submitted PR #414 for this: #414

It adds the PR size workflow, .prsize-ignore, warning/failure thresholds, the large-pr-approved bypass, and CONTRIBUTING documentation.

[DaddyMord]

@DaddyMord has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello Maintainer, I’d love to take ownership of this issue and submit a high-quality pull request once completed.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @DaddyMord to this issue.