Ingest note transport docs

[BrianSeong99]

Summary

Adds Note Transport to the docs site under Build > Tools and wires the deploy workflow to ingest source-owned docs from 0xMiden/note-transport-service.

What changed

• Adds current and v0.14 Note Transport docs pages.
• Adds the Note Transport sidebar section and Tools landing-page card.
• Adds a deploy workflow checkout for 0xMiden/note-transport-service with a note_transport_ref override.
• Preserves the committed snapshot when the vendor repo does not yet expose docs/external/src, so this PR can merge safely around Add source-owned note transport docs note-transport-service#87.
• Raises the Docusaurus build heap to 12GB after local full-site builds OOMed at 6GB.

Verification

• Full docs build in a clean temp tree with ingested vendor docs: NODE_OPTIONS=--max-old-space-size=12288 npm run build
• Verified generated pages for /next/builder/tools/note-transport/ and /builder/tools/note-transport/
• git diff --check

Notes

The full docs build still reports existing broken-link and broken-anchor warnings unrelated to these Note Transport pages.