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

frontend/src/lib/components/MediaVersionThumb.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
   import { type MediaResult, requestMediaVersion } from "$lib/api/client";
-  import { visualKind } from "$lib/api/media";
+  import { isActiveContent, visualKind } from "$lib/api/media";
   import type { MediaVersion } from "$lib/api/types";
   import Icon from "$lib/components/ui/Icon.svelte";
   import Spinner from "$lib/components/ui/Spinner.svelte";
@@ -48,7 +48,13 @@
       <span class="play"><Icon name="large-play" size="1.5rem" /></span>
     </a>
   {:else if result.state === "ready"}
-    <a class="file" href={result.url} target="_blank" rel="noopener">
+    <a
+      class="file"
+      href={result.url}
+      target="_blank"
+      rel="noopener"
+      download={isActiveContent(result.mime) ? `media_${version.id}` : undefined}
+    >
       <Icon name="document" size="1.125rem" />
       <span>{version.kind}</span>
     </a>