Make the cross-site API reference readable (full-width inline view plus a standalone full-page Redoc)

The cross-site API reference (docs/api.md) embeds Redoc inline. Redoc is a full-width, three-pane application, but the Material theme constrains page content to a narrow centered column, so the three panes are crushed together and the reference is effectively unusable (the response-samples panel wraps about one character per line).

Proposed resolution

• Give the API page room: hide the left navigation and right table of contents on docs/api.md and drop the content max-width for that page only (scoped to pages that contain a Redoc element), so the inline reference renders full-width.
• Add a standalone, chrome-free full-page reference at docs/api-reference.html (Redoc on its own page), linked from the API page with a small "full-page reference" link.
• Exclude docs/api-reference.html from cspell (HTML boilerplate, not prose) and enable the attr_list markdown extension for the link attributes.

Documentation tooling only; no functional code changes.