B-Z6X5-obsidian-md-plugins-subpath
Two consumers want the remark plugins without the render/Vue stack: obsidian-astro (delegating its wikilink plugin — blocked on this plus the buildNode seam, which landed with the ReDoS hardening) and any Astro docs site (the df-docs convergence entry). The root export is already Vue-free and shiki is behind a dynamic import, so no package split is warranted: add a ./plugins subpath export, and move mermaid/katex out of hard dependencies (they are imported only by the Vue components, dynamically). Do this after the notes stack has rebased over the carve (#1225) so divergence stays a single event.