fix(docs): keep agent links readable from the deployed portal

[NWYLZW]

Summary

• Use canonical raw document URLs for the Docs Skill and availability guide from llms.txt and the task index.
• Preserve the existing static portal publication configuration and bundled Skill bytes.

Evidence

• The deployed portal returns HTTP 200 for llms.txt and skills/index.md, but the relative SKILL.md target returns HTTP 404.
• Both replacement canonical raw-document targets return HTTP 200.
• Scoped dprint and git diff checks passed.
• No runtime, bundle or layout changes.