feat(ui): console redesign — sidebar, overview, list and inspector pages, a design system

[V3RON]

Redesigns the web console for operators: a sidebar, a fleet overview with charts, and list + inspector pages with less text.

What changes

• Sidebar in place of the top bar; collapses to icons, remembered per browser. The wordmark drops "gateway".
• Overview: stat tiles, a lease chart for the last hour, capacity per platform, workers, attention, activity.
• Workers, Leases, Waiting, Attention, Events: a list and an inspector; the URL names the chosen item.
• A worker row is a square, a name and running / limit. Memory pressure is yellow, disconnected red.
• The lease page puts the live screen on the right and its cards on the left.

Architecture

ui/src is split into model (pure rules), data (API, network, storage), state (hooks), ds (the design system) and screens (presentation only). .dependency-cruiser.mjs enforces the layers; ui/AGENTS.md describes them.

Left out

Figures the daemon does not serve yet are gathered in #612.

Tests

• Unit tests: 347 passed.
• Console lane, Chromium, Firefox and WebKit: 321 passed.

Written by an agent.