fix(frontend): chips of the changes panel stay on top while the list scrolls

frontend/src/lib/components/feed/ChatChanges.svelte

@@ -32,8 +32,19 @@
 </script>
 
 {#if chatId !== null}
-  <FeedFilters {kind} onkind={pick} />
+  <div class="filters">
+    <FeedFilters {kind} onkind={pick} />
+  </div>
   {#key chatId}
     <FeedList {chatId} {kind} onopen={open} />
   {/key}
 {/if}
+
+<style lang="scss">
+  .filters {
+    position: sticky;
+    z-index: 1;
+    top: 0;
+    background-color: var(--color-background);
+  }
+</style>