fix: restore admin role in User type, use image logo

- Add "admin" back to User.role union to fix backend TS build
- Replace SVG PeonyIcon with logo.png image in Logo component

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/lib/components/logo/logo.svelte

@@ -1,13 +1,10 @@
 <script lang="ts">
   import { _ } from "svelte-i18n";
-  import PeonyIcon from "../icon/peony-icon.svelte";
 
   const { hideName = false } = $props();
 </script>
 
-<div class="relative">
-  <PeonyIcon class="w-13 h-13 text-black" />
-</div>
+<img src="/logo.png" alt={$_("brand.name")} class="w-10 h-10 object-contain" />
 <span
   class={`logo text-3xl text-foreground opacity-90 tracking-wide font-extrabold drop-shadow-x ${hideName ? "hidden sm:inline-block" : ""}`}
 >