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/static/favicon.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" fill="none">
+	<rect width="32" height="32" rx="8" fill="#4F46E5"/>
+	<path d="M8 10.5h7.5a3.5 3.5 0 0 1 0 7H11v4H8v-11Zm3 4.5h4.5a1.5 1.5 0 0 0 0-3H11v3Z" fill="white"/>
+	<path d="M20.5 21.5c1.93 0 3.5-1.34 3.5-3s-1.57-3-3.5-3S17 16.84 17 18.5s1.57 3 3.5 3Z" fill="white" opacity=".9"/>
+</svg>

hub/database-admin/static/robots.txt

@@ -0,0 +1,3 @@
+# allow crawling everything by default
+User-agent: *
+Disallow: