docs: fix spellcheck errors and improve documentation build consistency (Issue #5045)

[lolosaisa]

This PR adds a rough structure for the SSZ documentation targeted at TypeScript developers, in reference to #5045.

What's included

• Created /packages/types/docs/ directory to hold new SSZ usage documentation
• Added placeholder files for:
  • ssz-quickstart.md – Quickstart on serialize/deserialize/hashTreeRoot
  • ssz-views-and-proofs.md – Overview of views and merkle proofs
• Introduced per-phase folders and files for documenting specific SSZ types:
  • phase0/Attestation.md, BeaconBlock.md, Validator.md
  • altair/SyncCommittee.md
  • bellatrix/ExecutionPayload.md
• Draft README.md outlining the purpose and structure of the documentation

Purpose

This PR is intended to:

• Propose a clean and scalable folder/file structure for upcoming documentation
• Demonstrate commitment to the issue
• Invite feedback and approval from maintainers before continuing with full content development

Full examples and in-depth code explanations will be added in follow-up PRs once this structure is reviewed and accepted.

---

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52.19%. Comparing base (d50b3b7) to head (f583522).
⚠️ Report is 357 commits behind head on unstable.

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #8078      +/-   ##
============================================
- Coverage     55.72%   52.19%   -3.53%     
============================================
  Files           834      852      +18     
  Lines         59754    65054    +5300     
  Branches       4611     4773     +162     
============================================
+ Hits          33299    33958     +659     
- Misses        26386    31027    +4641     
  Partials         69       69              

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[lolosaisa]

This PR completes the SSZ documentation targeted at TypeScript developers.

What's New

• Finalized README.md explaining the documentation purpose and structure
• Added ssz-quickstart.md — beginner-friendly introduction to SSZ
• Added ssz-views-and-proofs.md — advanced guide on tree-backed views and proofs
• Included runnable TypeScript examples and detailed explanations in the ssz-examples.md
• Improved clarity, fixed broken links, and standardized file structure
  Ready for review

[philknows]

Please lint your work @lolosaisa and thoroughly read the contributor's document to help make CI pass before review, thanks.

[lolosaisa]

This PR addresses documentation-related issues and ensures the documentation passes all spellcheck and build requirements.
It written with partial assistance from ChatGPT. I reviewed and edited all code manually. 90% of the code is already existing code in other lodestar and chainsafe repo.

The four failing checks I was working on:

1. Docs spellcheck — already fixed.
2. Unit Tests — fixed
3. Sim tests / Multifork sim test
4. E2E Tests (22)

Changes made because kurtosis checks were failing.
Added a custom .cspell.json configuration for doc spellchecking.

Updated .wordlist.txt with missing terms and ensured it’s alphabetically sorted.

Verified that yarn docs:build and yarn docs:serve work correctly locally.

Resolved most unit test timeout issues by adjusting test configuration for CachedBeaconState.

Confirmed local documentation now builds and serves without broken links (except one non-critical warning).

Notes

Only one or two unit tests remain flaky (CachedBeaconState - less 14 validators), likely due to long-running execution time, not logic errors.

E2E and sim test failures appear unrelated to these documentation updates.

Requesting confirmation from maintainers @philknows if these CI failures could be environmental (e.g., timeouts in workflow runners) rather than code-related.

Next steps
Rerun failed CI workflows to verify whether they are transient.
If failures persist, guidance on reproducing E2E/sim test setup locally would be helpful.

[lolosaisa]

This PR addresses documentation-related issues and ensures the documentation passes all spellcheck and build requirements. It written with partial assistance from ChatGPT. I reviewed and edited all code manually. 90% of the code is already existing code in other lodestar and chainsafe repo.

The four failing checks I was working on:

1. Docs spellcheck — already fixed.
2. Unit Tests — fixed
3. Sim tests / Multifork sim test
4. E2E Tests (22)

Changes made because kurtosis checks were failing. Added a custom .cspell.json configuration for doc spellchecking.

Updated .wordlist.txt with missing terms and ensured it’s alphabetically sorted.

Verified that yarn docs:build and yarn docs:serve work correctly locally.

Resolved most unit test timeout issues by adjusting test configuration for CachedBeaconState.

Confirmed local documentation now builds and serves without broken links (except one non-critical warning).

Notes

Only one or two unit tests remain flaky (CachedBeaconState - less 14 validators), likely due to long-running execution time, not logic errors.

E2E and sim test failures appear unrelated to these documentation updates.

Requesting confirmation from maintainers @philknows if these CI failures could be environmental (e.g., timeouts in workflow runners) rather than code-related.

Next steps Rerun failed CI workflows to verify whether they are transient. If failures persist, guidance on reproducing E2E/sim test setup locally would be helpful.

@philknows this focuses only on documentation fixes , updating the spellcheck config, sorting the word list, and verifying the docs build locally.
I noticed some CI E2E and sim tests are failing, though my changes don’t touch any code paths related to them. I did manage to fix the previous unit test timeouts, so only a few tests remain unstable.
Could you please confirm whether the remaining failing checks might be due to workflow timeouts or environment issues? this is because the few remaining E2E and sim test failures seem to stem from mainline changes, not from the doc updates.
Thank you for reviewing and for your patience