fix(frontend): paint video poster frames, clip round videos to circle

frontend/src/lib/media/poster.ts

@@ -0,0 +1,20 @@
+export const POSTER_TIME = 0.001;
+
+export function poster(node: HTMLVideoElement) {
+  const seek = () => {
+    if (node.currentTime === 0) {
+      node.currentTime = POSTER_TIME;
+    }
+  };
+
+  node.addEventListener("loadedmetadata", seek);
+  if (node.readyState >= node.HAVE_METADATA) {
+    seek();
+  }
+
+  return {
+    destroy() {
+      node.removeEventListener("loadedmetadata", seek);
+    },
+  };
+}