Repair frontend-to-docs canonical route coverage

[Hallab7]

Description

Frontend links for seller, buyer, agent, and operator guidance do not all resolve to real top-level docs routes.

Scope

In scope: Create or redirect stable canonical routes and add cross-repository link fixtures.

Out of scope: Do not preserve broken paths only for appearance.

Relevant files

docs; sidebars.js; scripts/check-links.mjs

Acceptance criteria

• Every published frontend docs URL returns success
• Redirects are intentional and tested
• Route ownership is documented
• Link checks include deployed base paths

Validation requirements

• Run npm run lint
• Run npm run links
• Run npm run check:content and npm run check:consistency
• Run npm run build

Security and protocol constraints

• Use synthetic or explicitly public testnet data only.
• Never commit secrets, seed phrases, private keys, signed private payloads, or production records.
• Keep unsupported network and payment capabilities fail closed and accurately labeled.

Drips complexity

Medium

Suggested branch

docs/repair-frontend-to-docs-canonical-route-coverage

PR requirements

• Keep the pull request scoped to this issue.
• Include exact validation evidence and update affected documentation.
• Use Closes #[issue number] in the pull request description.