Phase 24: Design System v2 — analytics-style UI (0.30.0)

- New /api/dashboard/funnel (5-stage stack health, 30s TTL cache) and
  /api/dashboard/summary (containers, daily uptime jsonl, ops activity)
- Token system (tokens.css + Tailwind sp-* aliases); legacy bg/card/accent
  remapped onto the tokens; Schibsted Grotesk bundled via fontsource
- TopNav pill navigation + AppShell replace the sidebar layout (off-canvas
  drawer below 1024px); central display-weight page titles
- Dashboard redesign: FunnelChart (gradient/hatch SVG waterfall), container
  count card with per-host bars + Insights chip, UptimeChart, OpsGrid,
  AiPromptBar; 30/7-day range selector; host sections retained below
- Stacks page honours ?q= / ?filter= deep links + new status-filter select

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/pages/StackDetail.tsx

@@ -50,7 +50,7 @@ export function StackDetail() {
         <div>
           <div className="flex items-center gap-2">
             <StatusDot status={data.status} />
-            <h1 className="text-xl font-bold">{data.name}</h1>
+            <h1 className="sp-heading text-xl">{data.name}</h1>
             <Badge status={data.status}>{data.status}</Badge>
           </div>
           {data.description && (