weichen
4f3b22d601
Why: D1-D5 were settled by the user (deps in, full-fidelity pptx, OG card plus optional embed, dual placement); the proposal status must reflect that before implementation starts. Evidence: decision section rewritten with the settled choices and the accepted trade-off on D2 (fall back to outline level with evidence only if no Vite-compatible renderer builds). Impact: documentation only. Refs: task feature/file-preview-caps.