Document Shamir mnemonic recovery

[ihsraham]

Deliverables

• Add a source-backed Shamir Secret Sharing guide for splitting, storing, verifying, and recovering English BIP-39 mnemonics.
• Correct the WDK Utils configuration and API reference for package-root imports, Node.js/browser/React Native randomness, share constraints, Promise failures, and compatibility limits.
• Add the guide to the WDK Utils overview and sidebar in Guides, before Configuration and API Reference.
• Regenerate llms.txt and llms-full.txt with 330/330 source-route parity.

Source baseline

• @tetherto/wdk-utils@1.0.0-beta.11
• Shamir implementation PR #34, first shipped in v1.0.0-beta.10

This is a root-exported WDK Utils capability, not a standalone package or @tetherto/wdk-utils/shamir subpath. The source checksum is an integrity check, not share authentication; the guide requires applications to authenticate exact share bytes and validate the recovered wallet identity against an independently protected public identifier.

Validation

• Node.js 22.22.2: npm ci
• Production static build: npm run build — 336/336 routes generated, 330 per-page Markdown files, and 0 broken built links
• LINK_CHECK_EXTERNAL=false npm run check:links — 330 MDX files, 2,743 links, 0 internal or anchor errors
• npm run test:link-routing, npm run check:meta, npm run check:redirects, and npm run test:llm-md
• Local static HTTP checks — guide, WDK Utils pages, per-page Markdown, llms.txt, and llms-full.txt returned 200 with expected content types
• WDK Utils source verification — 39/39 focused Shamir tests and lint passed

External-crawl note: the unrestricted repository link checker currently reports one untouched VS Code MCP URL as 404; the changed routes and production build link scan are clean.

[ihsraham]

Superseded by #229, which uses the upstream topic branch in tetherto/wdk-docs.