REL-545: add repository weight guardrails

[ryan10sa-star]

Summary

• document the repo-weight root cause and audit-friendly blobless sparse clone path
• add ignore rules for generated decks/images and framework build caches
• keep branch/ref cleanup as an explicit follow-up because it is history-affecting

Evidence

• GitHub disk usage is about 1,190,853 KB
• current main tree is about 942 KB
• metadata-only scan across 305 commits / 286 unique trees found about 1.26 GB of unique historical blob bytes
• largest sources are generated presentation/image artifacts on a stale side branch plus a smaller Next.js cache commit

Validation

• git diff --check
• blobless sparse checkout remained under 5 MB locally

---

^{Need help on this PR? Tag /codesmith with what you need. Autofix is disabled.}

[Copilot]

Pull request overview

Adds documentation and repository-level ignore rules to help keep the repo lightweight for audits and prevent reintroducing large generated artifacts.

Changes:

• Documented an “audit-friendly” blobless sparse-clone workflow in the README.
• Added docs/REPOSITORY_WEIGHT.md capturing the weight audit, known historical blob sources, and a cleanup/guardrails plan.
• Expanded .gitignore to exclude common Next.js/Vercel build outputs and known bulky generated media/artifact paths.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
README.md	Adds concise instructions for blobless sparse cloning and links to the weight audit doc.
docs/REPOSITORY_WEIGHT.md	New doc detailing current repo weight findings, historical blob sources, and audit/cleanup guidance.
.gitignore	Adds ignore rules for Next.js/Vercel outputs and generated decks/images/archive artifacts to prevent future bloat.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: b51ecb9ea1

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Fix sparse-checkout command that rejects README.md

For users following this audit path, the sparse checkout fails at this line because git clone --sparse uses cone-mode sparse checkout, and cone mode rejects file paths in git sparse-checkout set; reproducing with Git 2.43 reports fatal: 'README.md' is not a directory; to treat it as a directory anyway, rerun with --skip-checks. The same failing command is also added to the README, so the documented lightweight clone path does not work unless README.md is removed from the set list or the command switches modes/uses the appropriate flag.

Useful? React with 👍 / 👎.