Full design spec for the flyon-ui-based shell rework. All 7 design
sections (build system, sidebar, topbar, cards, forms/slide-panel,
states/motion, a11y/responsive/rollout) approved by user during
brainstorming. Next step is the implementation plan via writing-plans.
Captures the full commit list, current cluster state, the 172.18 LAN topology gotcha, the remaining recorders.html UI rewrite, and how the next agent should pick it up.
