Simplify host overview and move enrollment into drawer

src/lib/server/hosts/overview.ts

@@ -0,0 +1,16 @@
+import { db } from '../db/index.js';
+import { listHosts } from './index.js';
+import { presentHostPreparation } from './preparation.js';
+import type { Host } from '../../hosts.js';
+
+export interface HostOverview extends Host { serverCount: number }
+
+/** Count assigned servers without loading their telemetry or historical placements. */
+export function hostOverview(): HostOverview[] {
+    const hosts = listHosts();
+    const counts = new Map((db().prepare(`SELECT i.host_id, COUNT(*) AS count FROM native_instances i
+        JOIN servers s ON s.name = i.server
+        WHERE i.retired_at IS NULL AND s.destroyed_at IS NULL
+        GROUP BY i.host_id`).all() as { host_id: string; count: number }[]).map(row => [row.host_id, row.count]));
+    return hosts.map(host => ({ ...presentHostPreparation(host), serverCount: counts.get(host.id) ?? 0 }));
+}