Improve timeline scroll, media layout, avatars, and emoji coverage.

Remember room scroll position across switches, reserve image/video heights from Matrix dimensions, cache authenticated media blobs for avatars, restore jumbo emoji-only messages, and extend emoji font unicode-range for Unicode 15 glyphs.

package.json

@@ -8,7 +8,7 @@
     "node": ">=16.0.0"
   },
   "scripts": {
-    "start": "vite --open false",
+    "start": "vite",
     "build": "vite build",
     "lint": "yarn check:eslint && yarn check:prettier",
     "check:eslint": "eslint src/*",