Phase A+ — In-Deck Ranking, Shared Nav Chrome, and a Working /play Runtime
After Phase A landed `@dididecks/shell` with a working TOC + slide-ranking API + decomposition-stub generator, three concrete gaps surfaced on first founder smoke-test: no global navigation chrome connecting Scroll · TOC · Play, no way to rank a slide *from within* the scroll deck (you have to leave for a separate route), and nothing to verify the /play runtime works because the shell injects no /play route yet and chroma has no per-slide files for one to render. Phase A+ closes all three together — shell-injected global nav, a shell-exported `<SlideRankPill>` floating overlay the founder drops into the scroll deck via data-attrs, a minimum-viable `/play/[deckSlug]/[variantSlug]/[slot]?` route with ← / → keyboard nav, and two seeded per-slide files in chroma so the whole loop (rank → decompose → recreate → present) is provable end-to-end. All in workspace-link mode; Phase A.7's publish step is orthogonal.