feat(canvas): brand tech icons on services, matching site preview

Resolve a service's tech (postgres, redis, go, node, nginx, kafka,
~50 slugs) from its image/name and render the Simple Icons logo in
the tinted icon tile — canvas nodes, inspector, service detail
header, and database rows — with graceful fallback to type icons.
Demo services get resolvable images, ports, and domains; a Redis
Cache service joins Core Platform so the demo canvas mirrors the
landing preview (5 services, web/api/worker → api → postgres/redis).

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/frontend/src/features/workspace/canvas/ServiceIcon.tsx

@@ -0,0 +1,26 @@
+import { useState } from 'react';
+import { serviceIcon, serviceIconUrl, serviceTypeIcon, type ServiceIconInput } from './service-visuals';
+
+export function ServiceIcon({
+  service,
+  size = 16,
+}: {
+  service: ServiceIconInput;
+  size?: number;
+}) {
+  const [failed, setFailed] = useState(false);
+  const brand = serviceIcon(service);
+  if (brand && !failed) {
+    return (
+      <img
+        src={serviceIconUrl(brand)}
+        width={size}
+        height={size}
+        alt=""
+        loading="lazy"
+        onError={() => setFailed(true)}
+      />
+    );
+  }
+  return serviceTypeIcon(service.type ?? 'service', size);
+}