Single 🔗 button in the Shell header (direction 1 of 3 proposed on the
issue) — one fixed element regardless of link count, so it can't
clutter as the list grows, and visible on every route since Shell
wraps all of them. Opens a popover listing whatever GET /api/links
returns (icon + label, opens in a new tab); hidden entirely when the
list is empty, same "don't render a dead affordance" rule the old
dashboard's H0M3 tiles follow for Forge/Matrix.
Docs: docs/swarm/ui.md gets a short section on the feature + the
contribute-your-own-entry idiom.
Verified: npm run build + npm run typecheck clean, headless-chromium
screenshots of both the closed and (temporarily forced open for the
screenshot only) open states, pixel-sampled to confirm the popover is
actually using the dark theme vars and not just looking that way in a
downscaled preview.
8542f2ca42