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.

package.json

@@ -8,7 +8,7 @@
     "node": ">=16.0.0"
   },
   "scripts": {
-    "start": "vite --open false",
+    "start": "vite --no-open",
     "build": "vite build",
     "lint": "yarn check:eslint && yarn check:prettier",
     "check:eslint": "eslint src/*",