feat: apply imported design (bento grid, real elevation tokens, live indicator)

Imports the visual direction from a claude.ai/design session ("PulseNode
Dashboard.dc.html") and reconciles it with the app's existing choices
rather than a wholesale swap: kept the IBM Plex Sans/Mono + Space
Grotesk typography and the pulse-green accent concept from the earlier
pass, adopted the imported design's structural ideas - a real
tonal/elevation token system (derived divider/muted colors via
color-mix instead of hardcoded per-theme duplicates, actual box-shadow
elevation), a 12-column bento grid with per-widget-type column spans
instead of uniform equal-width cards, fading-edge section dividers,
and a shared WidgetCard/MetricBar/StatusTag vocabulary so every widget
type stops repeating its own card markup.

Icons come from @phosphor-icons/react's /ssr entrypoint (bundled at
build time) rather than the imported design's unpkg.com CDN script -
that script is fine for the standalone design-tool preview, but a
runtime third-party call would break the self-hosted-only principle
already established (fonts self-hosted via next/font, no external
requests). New app/icon.svg reuses the same nav badge mark as the
favicon, replacing the never-touched create-next-app default.

Two new pieces of real functionality prompted by the design's mockup
toast/live-indicator, not just decoration: a "live" WebSocket
connection-status indicator (lib/ws/client.ts now tracks and exposes
real connection state), and a toast that fires on actual config:update
and config:error events - the latter finally surfaces config validation
failures in the browser, previously visible only in server logs despite
being designed for exactly this back in M1.

components/widgets/database/Widget.tsx

@@ -3,6 +3,7 @@
 import type { Widget } from "@/lib/config/schema";
 import { useWidgetSubscription } from "@/lib/ws/client";
 import { StatusDot } from "@/components/widgets/StatusDot";
+import { WidgetCard } from "@/components/widgets/WidgetCard";
 import { formatUptime } from "@/lib/format";
 
 type DatabaseWidget = Extract<Widget, { type: "database" }>;
@@ -18,18 +19,18 @@ export function DatabaseWidget({ widget, widgetId }: { widget: DatabaseWidget; w
   const errorMessage = result?.type === "error" ? result.message : null;
 
   return (
-    <div className="flex flex-col gap-2 rounded-[var(--radius-widget)] border border-border bg-surface p-4">
+    <WidgetCard span={4}>
       <div className="flex items-center justify-between gap-2">
-        <span className="text-sm font-medium text-fg">{widget.name}</span>
+        <span className="text-[15px] font-medium text-fg">{widget.name}</span>
         <StatusDot status={data?.status} health={data?.health} />
       </div>
-      <span className="text-xs text-fg-muted">{ENGINE_LABEL[widget.engine]}</span>
+      <span className="text-[11px] text-fg-muted">{ENGINE_LABEL[widget.engine]}</span>
       {errorMessage && <span className="text-xs text-status-down">{errorMessage}</span>}
       {data?.uptimeSeconds != null && (
-        <span className="text-xs text-fg-muted">
-          Uptime: <span className="font-mono tabular-nums text-fg">{formatUptime(data.uptimeSeconds)}</span>
+        <span className="text-[11px] text-fg-muted">
+          up <span className="font-mono tabular-nums text-fg">{formatUptime(data.uptimeSeconds)}</span>
         </span>
       )}
-    </div>
+    </WidgetCard>
   );
 }