fix(api,frontend): isolate active share files and allowlist link schemes

frontend/src/lib/components/WebPage.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
   import type { MessageView } from "$lib/api/types";
   import MessageMedia from "$lib/components/MessageMedia.svelte";
+  import { safeHref } from "$lib/format/url";
 
   interface Props {
     message: MessageView;
@@ -20,7 +21,7 @@
         <MessageMedia {message} {own} onopen={() => onmedia(0)} />
       </div>
     {/if}
-    <a class="card" href={web.url} target="_blank" rel="noopener">
+    <a class="card" href={safeHref(web.url)} target="_blank" rel="noopener">
       {#if web.site_name}
         <div class="site">{web.site_name}</div>
       {:else if web.display_url}