feat(topology): overhaul network topology with dagre layout, enriched nodes, and click-to-logs (#447)

Replace N+1 Docker API calls (inspectNetwork per network) with a
container-centric approach that fetches all networks and containers
in 2 parallel calls, then maps relationships in memory.

Add dagre auto-layout algorithm for hierarchical DAG visualization,
replacing the static two-row layout that caused edge spaghetti at scale.

Add "Show system networks" toggle, enrich container nodes with running
state indicators, stack badges, and base image names. Clicking a
running container opens its log viewer directly from the topology graph.

frontend/src/lib/events.ts

@@ -0,0 +1,8 @@
+/** Cross-component custom event constants and typed detail interfaces. */
+
+export const SENCHO_OPEN_LOGS_EVENT = 'sencho-open-logs';
+
+export interface SenchoOpenLogsDetail {
+  containerId: string;
+  containerName: string;
+}