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/routes/admin/+page.svelte

@@ -0,0 +1,78 @@
+<script lang="ts">
+	import { onMount } from 'svelte';
+	import { goto } from '$app/navigation';
+	import { base } from '$app/paths';
+	import { api, type DatabaseConfig } from '$lib/api';
+	import { feishuLoginHref } from '$lib/session';
+	import Aurora from '$lib/components/Aurora.svelte';
+
+	let config = $state<DatabaseConfig | null>(null);
+	let error = $state<string | null>(null);
+
+	onMount(async () => {
+		// Already signed in → straight to the dashboard.
+		try {
+			await api.me();
+			await goto(`${base}/dashboard`, { replaceState: true });
+			return;
+		} catch {
+			// Not signed in (401) or backend unreachable — show the login card.
+		}
+		try {
+			config = await api.databaseConfig();
+		} catch (err) {
+			error = err instanceof Error ? err.message : String(err);
+		}
+	});
+
+	const feishuHref = $derived(config ? feishuLoginHref(config.siloOrganizationSlug) : '#');
+</script>
+
+<Aurora />
+
+<main class="flex min-h-screen items-center justify-center p-4">
+	<div class="rise glass relative w-full max-w-sm rounded-3xl border border-white/80 p-8 shadow-2xl shadow-indigo-200/50">
+		<div class="mb-7 text-center">
+			<div
+				class="mx-auto mb-5 flex h-14 w-14 items-center justify-center rounded-2xl bg-gradient-to-br from-violet-500 to-cyan-400 text-2xl font-bold text-white glow-btn"
+			>
+				D
+			</div>
+			<h1 class="text-2xl font-bold tracking-tight grad-text">Database Admin</h1>
+			<p class="mt-2 text-sm text-slate-500">使用飞书登录以管理数据库</p>
+		</div>
+
+		{#if error}
+			<div class="mb-4 rounded-xl border border-red-200 bg-red-50 px-4 py-3 text-sm text-red-600">
+				无法连接后端：{error}
+			</div>
+		{/if}
+
+		<a
+			href={feishuHref}
+			aria-disabled={config ? 'false' : 'true'}
+			class="rise-2 glow-btn group flex w-full items-center justify-center gap-2 rounded-xl bg-gradient-to-r from-violet-500 to-indigo-500 px-4 py-3.5 text-sm font-semibold text-white transition hover:from-violet-400 hover:to-indigo-400 aria-disabled:pointer-events-none aria-disabled:opacity-50"
+		>
+			<svg class="h-4 w-4" viewBox="0 0 24 24" fill="currentColor">
+				<path d="M12 2 3 7v10l9 5 9-5V7l-9-5Zm0 2.3 6.5 3.6L12 11.5 5.5 7.9 12 4.3Z" />
+			</svg>
+			使用飞书登录
+		</a>
+
+		{#if config?.devLoginEnabled}
+			<div class="relative my-6 rise-3">
+				<div class="absolute inset-0 flex items-center"><div class="w-full border-t border-slate-200"></div></div>
+				<div class="relative flex justify-center">
+					<span class="bg-white/70 px-3 text-[11px] font-medium uppercase tracking-[0.2em] text-slate-400">开发模式</span>
+				</div>
+			</div>
+			<a
+				href="/database/dev-login"
+				class="rise-3 group flex w-full items-center justify-center gap-2 rounded-xl border border-amber-300 bg-amber-50 px-4 py-3 text-sm font-semibold text-amber-700 transition hover:border-amber-400 hover:bg-amber-100"
+			>
+				<span>⚡</span> 一键登录管理员
+			</a>
+			<p class="rise-3 mt-2 text-center text-xs text-slate-400">仅开发环境可见 · 跳过飞书 OAuth</p>
+		{/if}
+	</div>
+</main>