Convert the 3 open TODO.md items into sequential phases appended to the
existing pipeline (Protocol B, numbered after 179):
- 180_markdown_inline_links_images: the shared escape-first renderer
gains the [text](url) link transform, the  image
transform, and the ####-###### heading levels, with CSS and the
dedicated Playwright suite.
- 181_svg_document_preview: SVGs index as vector image documents
(text extracted from title/desc/text, no vision call), are served as
sandboxed image/svg+xml, and preview as graphics instead of raw XML.
TODO.md is cleared; its items now live in .agents/phases/.
LLM-Generated: true
