feat(hub): migrate database admin pages to SPA (database-admin)

- scaffold hub/database-admin as SvelteKit 2 + Svelte 5 static SPA
  with aurora/glass visual style (paths.base='/database')
- add lib/{api,session,org}.ts + Aurora.svelte component
- add routes: root redirect, /admin login page, /dashboard (OWNER/ADMIN only)
- backend: replace server-rendered HTML routes with /database/config JSON endpoint
- add hub/src/database/static.ts to serve SPA under /database/*
- wire registerDatabaseSpa into plugin.ts
- exempt /database/* from silo rate-limit (same treatment as /admin/*)
- add database:dev + database:build npm scripts; update deploy scripts
- update hub/src/database/README.md

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hub/database-admin/src/lib/org.ts

@@ -0,0 +1,7 @@
+import type { OrgMembership } from './api';
+
+export function isOrgAdmin(org: OrgMembership | null | undefined): boolean {
+	if (!org) return false;
+	const role = String(org.role ?? '').toUpperCase();
+	return role === 'OWNER' || role === 'ADMIN';
+}