remove old placeholder algorithm

- TootPreviewCard and MediaAttachmentGrid
- the placeholder thing is now offloaded to the
  browser

src/timelines/RegularToot.tsx

@@ -7,6 +7,7 @@ import {
   createRenderEffect,
   createSignal,
   createEffect,
+  type Accessor,
 } from "solid-js";
 import tootStyle from "./toot.module.css";
 import { formatRelative } from "date-fns";
@@ -306,6 +307,8 @@ export function TootPreviewCard(props: {
           crossOrigin="anonymous"
           src={props.src.image!}
           onLoad={onImgLoad}
+          width={props.src.width || undefined}
+          height={props.src.height || undefined}
           loading="lazy"
         />
       </Show>