Publish one relative image as a Doc Asset end-to-end

[wschenk]

Parent

#39

What to build

Extend doc publish so a Markdown file with a relative image reference uploads that file as a Doc Asset, rewrites the stored Living Doc Markdown to an absolute Unlisted URL under /d/{opaqueId}/{assetPath}, and leaves the View/Review surfaces able to load the image. Absolute http(s) image URLs stay unchanged. Duplicate relative refs to the same file upload once. Publisher-authenticated publish only (no Review Link upload).

Wire collector → uploader → rewriter → persist rewritten Markdown in an order that does not leave rewritten URLs pointing at missing Blob objects. CLI/API should return View and Review URLs as today. doc pull returns the rewritten Markdown.

Acceptance criteria

• Publishing Markdown with ![…](./…) (and ../…) uploads the image and stores rewritten hosted URLs in currentMarkdown
• The hosted image URL returns 200 on the View prefix after publish
• Absolute http(s) image URLs are not rewritten
• Duplicate relative refs to one file produce a single upload / single assetPath
• Orchestration tests with fake Blob + in-memory store cover happy path; mid-flight upload failure does not succeed with dangling hosted URLs
• Rewriter unit tests cover relative rewrite, absolute passthrough, and table-embedded image refs

Blocked by

• Serve Doc Assets under /d/{opaqueId}/{assetPath} #40