Improve media placeholders, avatar caching, and jumbo emoji layout.

Reserve image/video box size from info.w/h, fade in over blurhash blobs, cache dimensions/blurhashes and authenticated media blobs so avatars don't refetch every remount, and throttle TitleBar/DM reorder during sync catchup.

src/app/features/room/msgContent.ts

@@ -59,10 +59,14 @@ export const getImageMsgContent = async (
     [MATRIX_SPOILER_PROPERTY_NAME]: metadata.markedAsSpoiler,
   };
   if (imgEl) {
-    const blurHash = encodeBlurHash(imgEl, 512, scaleYDimension(imgEl.width, 512, imgEl.height));
+    const naturalW = imgEl.naturalWidth || imgEl.width;
+    const naturalH = imgEl.naturalHeight || imgEl.height;
+    const blurHash = encodeBlurHash(imgEl, 512, scaleYDimension(naturalW, 512, naturalH));
 
     content.info = {
       ...getImageInfo(imgEl, file),
+      w: naturalW,
+      h: naturalH,
       [MATRIX_BLUR_HASH_PROPERTY_NAME]: blurHash,
     };
   }