Make workspace Rustdoc warning-free and CI-enforced

[arniber21]

Parent

#377

What to build

Repair the Rust API documentation so every intra-doc link resolves in the public build, then make warning-free Rustdoc part of the declared documentation quality contract.

Acceptance criteria

• All unresolved, private-item, redundant-target, and output-collision warnings observed by workspace documentation generation are resolved.
• Literature citations render as citations rather than accidental intra-doc links.
• Public documentation does not depend on --document-private-items to resolve.
• CI generates workspace Rustdoc with warnings denied.
• The local validation documentation names the exact warning-denying command.

Blocked by

None - can start immediately.

[arniber21]

Implemented and merged via PR #450. Closing as complete.